I
Note: EPA no longer updates this information,
but it may be useful as a reference or resource. ;
& EPA
United Stales
Environmental Protection
Agency
Office of Air Quality
Planning and Standards
Research Triangle Park, NC 27711
EPA-452/R-92-010
November 1992
ATT
GUIDELINES FOR ESTIMATING
AND APPLYING RULE
EFFECTIVENESS FOR OZONE/CO
STATE IMPLEMENTATION PLAN
BASE YEAR INVENTORIES
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GUIDELINES FOR ESTIMATING AND APPLYING RULE EFFECTIVENESS FOR
OZONE/CO STATE IMPLEMENTATION FLAN
BASE YEAR INVENTORIES
Ozone and Carbon Monoxide Branch
Air Quality Management Division
Office of Air Quality Planning and Standards
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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ADDENDUM
After preparation of this document, EPA decided to recommend
additional flexibility in accounting for rule effectiveness (RE)
in the development of base year emission inventories. This
addendum provides guidance regarding that flexibility.
METHODS FOR ACCOUNTING FOR RULE EFFECTIVENESS FOR VOLATILE
ORGANIC COMPOUND (VOC) SOURCES
A State or local agency that prepares VOC emission inventories
may account for rule and control effectiveness by methods other
than those specified in this document. Deviations from methods
in document must meet the following criteria, as well as criteria
specified in "Documentation and Concurrence," below:
—In evaluating rule effectiveness under a method that
deviates from the guideline, the State should consider:
* _
—The overall capture and control efficiency generally
available from the kind of capture and control
equipment being assessed;
—Any stack test/performance evaluation that was
performed on the capture and control equipment;
—The rated capture and control efficiency (from
manufacturer's specifications or literature);
— The kinds of activities that affect the
determination of day-to-day performance of the capture
and control equipment that are listed in the
questionnaires that are contained in the guideline
document (e.g., ease of determining compliance, type of
control equipment, frequency and quality of
inspections, level of training of inspectors).
—The State or local agency should provide a way of
determining which sources have applied control to avoid
having planners "recontrol" already controlled sources.
METHODS FOR ACCOUNTING FOR RULE EFFECTIVENESS FOR SOURCES OF
OXIDES OF NITROGEN AND CARBON MONOXIDE
Rule effectiveness must be considered for sources of oxides
of nitrogen and carbon monoxide where such sources are covered by
rules or regulations in the State implementation plan (SIP). If
a State or local agency does not use either the questionnaire
method or the Stationary Source Compliance Division (SSCD)
protocol, that agency should develop its own method for assessing
RE and should not rely solely on the 80 percent default value.
11
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In evaluating rule effectiveness under such a method, the State
should consider the kinds of activities that are listed in the
questionnaires that are contained in the guideline document
(e.g., ease of determining compliance, type of control equipment,
frequency and quality of inspections, competence of inspectors).
Methods for accounting for rule effectiveness different from the
methods in the document must also meet the criteria specified in
"Documentation and Concurrence," below.
RARE CATASTROPHIC OR ACCIDENTAL RELEASES
Rare catastrophic or accidental releases may be inventoried
in a manner deemed appropriate by the State or local agency;
these releases do not necessarily need to be reflected in a rule
effectiveness assessment, unless there is a pattern of re-
occurrence. The methods developed must meet the criteria
specified in "Documentation and Concurrence," below.
DOCUMENTATION AND CONCURRENCE
* -^
The above paragraphs describe cases where methods that
deviate from the methods in this document may be employed. In
developing and using such a method, the following general
criteria must be met:
—The Regional Office, in consultation with the EPA Office
of Air Quality Planning and Standards, must concur on the
method. '
—Documentation must be available at the State or local
agency for inspection by EPA; documentation does not have to
be submitted with emission inventory.
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TABLE OF CONTENTS
Section
Page
Addendum ii
List of Tables vi
List of Figures vi
1 INTRODUCTION 1
1.1 Background 2
1.2 Meaning of Rule Effectiveness 3
1.3 Rule Effectiveness for Base Year Inventories 4
1.4 Factors Affecting Rule Effectiveness 5
1.5 Calculating and Applying Rule Effectiveness 5
1. 6 References 8
2 PROCEDURES FOR ESTIMATING CATEGORY-SPECIFIC RE ...... 9
2.1 Determining Sources for Application of Rule
Effectiveness 9
2.1.1 Excepted Sources 9
2.1.2 Direct Determination of Emissions 11
2.1.2.1 Criteria for Direct Determination
Emissions 12
2.1.2.2 Example of Direct Determination 12
2.1.2.3 Major Classes of Emissions
Estimation Techniques 13
2.1.2.4 Documenting Direct Determination .... 15
2.2 Overview of Applicable Approaches for
Determining RE 16
2.3 Default Value Approach 16
2.4 Questionnaire Approach 18
2.4.1 Level of Effort 18
2.4.2 Procedure 19
2.4.2.1 Identifying Personnel to Perform
the Evaluation 19
2.4.2.2 Preliminary Screening of Sources .... 19
2.4.2.3 Choosing Sources to Evaluate 20
2.4.2.4 Sources with Control Efficiencies
Greater Than 95 Percent 21
2.4.2.5 Answering the Questionnaires 22
2.4.2.6 Determination of Rule Effectiveness
Values 22
2.5 SSCD Study Approach 23
2.5.1 Purpose of the Study 23
2.5.2 Summary of the SS.CD Study
Approach Procedures 24
2.5.3 Calculating RE from an SSCD Study 25
2.6 Using Results from SSCD Studies,
Questionnaires and the Default 27
IV
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TABLE OF CONTENTS (continued)
Section
Page
3 APPLICATION OF RULE EFFECTIVENESS IN
BASE YEAR INVENTORIES 30
3.1 Introduction 30
3.2 Calculating Rule-Affected Emissions 30
3.2.1 Control Efficiency 31
3.2.2 AIRS Coding . . 33
3.3 Documenting Rule Effectiveness for the
SIP Submittal 34
3.4 References 34
4 EXAMPLE CALCULATIONS .....' 36
4.1 Point Sources 36
4.1.1 Bulk Terminals (Loading Racks) 36
4.1.2 Beverage Can Coating v 37
4.1.3 Paper Coating Facility .....* ~40
4.1.4 Metal Furniture Coating 40
4.1.5 Automobile Assembly Plant 41
4.1.6 Large Appliance Coating 42
4.1.7 Large Petroleum Dry Cleaner 43
4.1.8 Graphic Arts 43
4.2 Area Sources 45
4.2.1 Stage I (Area Source Category) 45
4.2.2 Architectural Coating
(Area Source Category) 46
APPENDIX A: RULE EFFECTIVENESS EVALUATION
FORM-POINT SOURCES A-l
APPENDIX B: RULE EFFECTIVENESS QUESTIONNAIRE-AREA
SOURCE CATEGORIES B-l
APPENDIX C: DIRECT DETERMINATION EXAMPLE C-l
APPENDIX D: DETERMINING SAMPLE SIZE D-l
APPENDIX E: DEFAULT CONTROL ASSUMPTIONS FOR
CTG CATEGORIES E-l
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LIST OF TABLES
Number Page
1-1 Factors Influencing Rule Effectiveness 6
1-2 Applying RE in Base Year SIP Inventories 7
2-1 Source Categories Covered by EPA Control
Techniques Guidelines (CTGs) 10
2-2 Direct Determination Scenarios . . . 12
2-3 Emission Estimation Methods . 14
2-4 Documenting Direct Determination for Surface Coating . . 17
2-5 Example of Weighted RE Value Using Questionnaire .... 24
2-6 Combining SSCD Study and Questionnaire Approaches .... 29
3-1 Default Petroleum Storage Tank Control Efficiencies ... 32
3-2 Coding RE in Electronic Inventory Submittals 34
D-l Sensitivity Analysis of Sample Size:
Confidence Level = 90% D-5
D-2 Sensitivity Analysis of Sample Size:
Confidence Level = 95% D-6
D-3 Sensitivity Analysis of Sample Size:
Confidence Level = 99% D-7
E-l Typical VOC Reduction per Facility for CTG Categories
Based on CTG Documents E-3
LIST OF FIGURES
Kumbar Page
2-1 Comparison of the Questionnaire and SSCD Study 28
VI
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SECTION 1
INTRODUCTION
Emission inventories are assembled with the intent to provide
the most accurate, representative emissions estimates available.
The 1990 Clean Air Act Amendments (CAAA) require base year annual
and daily actual emission inventories to be gathered as part of
the State implementation plan (SIP) for areas not in attainment
for the current ozone and/or carbon monoxide (CO) national
ambient air quality standards (NAAQS). These estimates are used
to support inventory projections, ambient modeling applications,
attainment strategy (regulatory) development and subsequent
(periodic) inventories.
Prior to the post-1987 SIP requirements, SIP inventories and
their applications assumed that regulatory programs for
stationary sources were being and would continue to be
implemented with full effectiveness, achieving all of the
reported, required or intended emission reductions, and
maintaining that level over time. However, experience during the
decade of the 1980s has shown these regulatory programs to be
less than 100 percent effective in achieving the necessary
emissions reductions in most areas of the country. This means
that SIP's before 1987 typically have understated actual
emissions in both the baseline and projected inventories,
resulting in lower emission reduction targets than were actually
necessary to attain the NAAQS.
To avoid these miscalculations and more accurately estimate
actual emissions, consideration shall be made for "rule
effectiveness." This document provides guidelines for
calculating and applying rule effectiveness in SIP base year
inventories. The concepts and procedures discussed herein
currently apply to ozone nonattainment area inventories, but will
be applicable to SIP inventories for other pollutants as the need
arises. This guidance focuses on developing estimates of rule
effectiveness (RE) for the inventory that are used to obtain more
realistic emission estimates for source categories.
This guidance describes the procedures developed by the
Office of Air Quality Planning and Standards (OAQPS) to estimate
the effectiveness of existing regulatory programs to achieve
emissions control for stationary sources. One approach is the
detailed study protocol developed by the Environmental Protection
Agency (EPA) Stationary Source Compliance Division (SSCD)
involving on-site inspection and testing on a single source
category by source category basis. The second approach,
developed by the Air Quality Management Division (AQMD), involves
answering generic questionnaires using available file information
for specific sources and extrapolating the results to other
sources in the same source categories. The third option is to
use the 80 percent default for estimating RE. The results-of
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these approaches are to be used to estimate RE for the base year
emission inventories being prepared in response to the 1990 CAAA
calls for ozone and CO SIP's.
The document is divided into four main sections. The
remainder of Section 1 discusses the definitions and roles of
various types of effectiveness measures that have historically
been referred to as "rule" effectiveness and introduces the
concepts covered in this guidance. Section 2 describes the
procedures to be used in estimating category-specific RE values
for States that choose not to use the 80 percent default.
Section 3 contains instructions on how to apply RE to sources in
the base year inventories, including a discussion of direct
determination of emissions. Section 4 provides RE examples to
aid in the calculation of emissions for base year inventories.
Appendices A and B contain the point and area source RE
questionnaires, respectively; Appendix C illustrates direct
determination and Appendix D provides statistical guidelines for
sample selection for the point source questionnaire. Appendix E
presents typical VOC emissions reductions for Control Techniques
Guideline categories.
1.1 BACKGROUND
On November 24, 1987, EPA proposed the post-1987 ozone/CO
policy.1 A key component of this policy was the proposal that
States account for the actual effectiveness of both present and
future regulatory programs. This measure was termed "rule"
effectiveness and represented the actual degree of source
compliance. For stationary sources, EPA proposed that a baseline
assumption of 80 percent RE should be applied to all regulated
source categories in the inventory until a local category-
specific evaluation could be completed to ascertain the actual
category-specific effectiveness. (This 80 percent default value
was initially based on a survey of several states that estimated
the actual effectiveness of their emissions rules.)
EPA received numerous comments regarding the RE requirements
proposed in that policy. None of the commenters challenged the
concept of applying RE in-the inventories or of improving the RE
of particularly troublesome categories. Many commenters,
however, suggested that EPA provide an alternative to the across-
the-board 80 percent presumption. The general theme contained in
these comments suggested that EPA should allow State and local
agencies flexibility in making RE estimates so that regulatory
programs showing good compliance rates for certain source
categories could receive higher credit than those showing lower
compliance rates.1
lrrhe issue of the creditability of RE improvements towards meeting reduction
goals is not discussed in this document. Creditability will be included in a
more general discussion of rule effectiveness in forthcoming guidance.
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EPA provided guidance to the States in preparing the new siPs
pursuant to Title I of the CAAA through the Federal Register
(General Preamble for Title I Implementation, April 16, 1992) .
EPA policy requires that base year stationary source inventories
of volatile organic compounds (VOCs), nitrogen oxides (NOJ and
carbon monoxide (CO) be adjusted for RE, using either the 80
percent default value or the results from one of the procedures
described herein.
1.2 MEANING OF RULE EFFECTIVENESS
RE reflects the ability of a regulatory program to achieve
all the emission reductions that could have been achieved by full
compliance with the applicable regulations at all. sources at all
times. The precise degree to which all affected sources comply
with a particular regulation over time is virtually impossible to
ascertain without continuously monitoring emissions at all
sources. RE can be estimated, however, by evaluating the success
of a regulatory program at a few sources and extrapolating the
results to others.
RE requires an understanding of a source's uncontrolled
emissions and the control placed on that source, rather than the
controlled emissions. As demonstrated in Section 4, the RE value
is applied to adjust the control efficiency and is not applied to
the emission estimate directly. For example, 80 percent RE means
the control effectiveness is actually 80 percent of the estimated
control efficiency; it does not mean that actual emissions are 20
percent greater than estimated.
The appropriate method for determining and using RE depends
upon the purpose for the determination: compliance, program or
inventory. RE discussed outside the particular purpose may be
generically referred to as control effectiveness. The following
three common uses for a control effectiveness estimate have
historically been called rule effectiveness:
• Identifying and addressing weaknesses in control
strategies and regulations related to compliance and
enforcement activities (more accurately called Compliance
Effectiveness)
• Defining or refining the control strategy necessary to
achieve the required emissions reductions designated in
the CAAA (more accurately called Program or SIP Design
Effectiveness)
Improving the accuracy or representativeness of emission
estimates across a nonattainment area (hereafter called
Rule Effectiveness)
Each user needs to determine the effectiveness of rules and
controls in reducing emissions to the desired level as it relates
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to the specific purpose. For example, SIP planners are concerned
with the ability of the SIP strategy to meet specific ambient
pollutant targets. Compliance personnel are interested in the
relationship between actual.and permissible emissions for a
particular source or source category. Inventory personnel need
to know the expected exceedance of emissions from the base
estimate. This document concentrates on RE; Program and
Compliance Effectiveness will be addressed in subsequent
guidance.
1.3 RULE EFFECTIVENESS FOR BASE YEAR INVENTORIES
The inventory RE is an adjustment to estimated emissions data
to account for emissions underestimates due to compliance
failures and the inability of most inventory techniques to
include these failures in an emission estimate. The RE
adjustment accounts for known underestimates due to noncompliance
with existing rules, control equipment downtime or operating
problems and process upsets. The result is a best estimate of
actual base year emissions, leading to more reliable estimates ef
expected emission reductions a-nd control measure effectiveness in
future years. EPA requires that base year SIP inventories apply
and report RE.3
Base year inventory RE considers that emission changes
brought on by growth, production changes, etc. are artifacts that
should be excluded when determining RE. RE simply adjusts the
estimated emissions for the effects of noncompliance. By
definition, all source categories for which a regulation exists
should have an RE value between zero arid 100 percent (i.e.,
source categories for which no regulation exists would have no RE
factor associated with them). To say that a particular
regulation was 100 percent effective would mean that the
regulatory agency could ensure complete and continual compliance
at all sources covered by the regulation, with no incidence of
control equipment failure or process upset at any source and no
sources evading control requirements. To say that a regulation
was zero percent effective would mean that no sources in the
category had made any effort to comply with the applicable
regulation. RE cannot be less than zero or greater than 100 by
definition.
The connection between SIP rules and actual emissions
reductions is that State or local agencies must assume that there
will be less than 100 percent compliance of rules in the absence
of other information. Otherwise, rules will not actually achieve
the intended reductions mandated in Section 182(b)(1) of the
CAAA: 15 percent over 6 years and 3 percent per year thereafter
until attainment is reached.
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1.4 FACTORS AFFECTING RULE EFFECTIVENESS
There is no succinct mathematical formula that adequately
accounts for the many different variables influencing RE,
although it can be thought of as a complex function of the
following types of factors: the nature of the regulation, the
nature of techniques used to comply with the regulation, the
performance of each source in complying with the regulation, and
the performance of the implementing agency in enforcing the
regulation. Table 1-1 lists specific examples of each type of
factor. The list is not exhaustive, however, it demonstrates the
large number and wide variety of factors that- affect RE.
1.5 CALCULATING AND APPLYING RULE EFFECTIVENESS
The remainder of this document explains the calculation of RE
values and the adjustment of base year emissions for RE. Every
base year SIP inventory must apply RE according to the guidelines
set forth herein. The process of examining and applying RE
entails the basic steps listed in Table 1-2. These steps are -
explained in detail in the following chapters.
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TABLE 1-1. FACTORS INFLUENCING ROLE EFFECTIVENESS
Nature of the Regulation
• possible ambiguity or deficiencies in wording
level of detail of recordkeeping required
level of complexity of compliance determination
inadequate test methods
Nature of Techniques Used to Comply with Regulation
level of confidence in long-term capabilities of control technique
(i.e., whether the emissions control is prone to failure or
degradation even with adequate attention)
• complexity of control technique (i.e., likelihood that operator
error or variability in operator technique could affect
compliance) *
potential for fugitive emissions not ducted to control device
(i.e., adequacy of emissions capture system)
Performance of Source in Complying With Regulation
• trained individual responsible for complying with environmental
regulations
schedule for maintenance and inspection of control equipment
adequacy of recordkeeping practices (i.e., can compliance be
determined from available records?)
ensurance of compliance over time, considering the previous record
of process upsets or control equipment malfunction
timeliness of response to notices of violation
Performance of Implementing Agency in Enforcing Regulation
attention and resources directed at this source or source category
communications effort, with respect to compliance requirements
completeness of data maintained on file
thoroughness in training inspection personnel
timeliness and thoroughness of inspections
adequacy of follow-up on noncomplying sources
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\
TABLE 1-2. APPLYING RE IN BASE YEAR SIP INVENTORIES
Step
Considerations
Determine
relevant
emissions
categories
Identify exempt
sources
Calculate a RE
value (%) for
each relevant
category
Calculate
control
efficiency for
each affected
source
Calculate base
year emissions
(adjusted for
RE)
Document RE
calculations
Source categories which are subject to
emission controls (i.e., there is a rule
in place) during the year of inventory
should be considered.
Emissions from sources with
uncontrolled, directly determined or
permanently eliminated emissions are
exempt from adjustment for RE.
Agencies calculate RE values derived
from an SSCD study, the questionnaires
included in this guidance or the default
value. Questionnaires require a survey
of sources in the categories identified
in the first step.
A reasonable estimate of the emissions
control efficiency for each source is
essential to the RE calculation. This
efficiency may be measured or estimated
based on the control device or estimated
based on the rule in place.
Emissions are adjusted for RE as
described in this document using
uncontrolled emissions, control
efficiency and the RE value; these
emissions are the SIP base year
emissions.
When submitting the SIP inventory,
agencies should document the procedures
and calculations made to show that RE
has been appropriately addressed,
including criteria used to exempt
sources.
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1.6 REFERENCES
1. State Implementation Plans; Approval of Post-1987 Ozone and
Carbon Monoxide Plan Revisions for Areas Not Attaining the
National Ambient Air Quality Standards; Notice, Federal
Register, Vol. 52, No. 226, November 24, 1987. pp. 45044-
45122.
2. U.S. Environmental Protection Agency, Procedures for
Estimating and Applying Rule Effectiveness in Post-1987 Base
Year Emission Inventories for Ozone and Carbon Monoxide State
Implementation Plans, Office of Air Quality Planning and
Standards, Research Triangle Park, NC, June 1989.
3. U.S. Environmental Protection Agency, Emission Inventory
Requirements for Ozone State Implementation Plans,
EPA-450/4-91-010, Office of Air Quality Planning and
Standards, Research Triangle Park, NC, March 1991.
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SECTION 2
PROCEDURES FOR ESTIMATING CATEGORY-SPECIFIC RE
2.1 DETERMINING SOURCES FOR APPLICATION OF RULE EFFECTIVENESS
Every source subject to an emission control regulation during
the inventory period should be considered for application of RE.
For many nonattainment areas, the list of Control Techniques
Guidelines (CTG) categories (Table 2-1) provides a starting point
to identify regulated sources. It is important to include all
regulated sources, regardless of whether the regulation had
received official EPA approval prior to the inventory period. In
some cases sources are exempted from emissions regulations if an
emission cap (e.g./ 25 tons VOC per year) is not exceeded as
defined by the emission control rule. These sources are not
necessarily subject to RE, although a State or local agency may
choose to include these sources if compliance with the emissions
cap is a known problem. Once the affected emissions categories
and sources have been identified, each source is ^reviewed to
determine the appropriate RE application.
2.1.1 Excepted Sources
The following sources are exempt from the RE adjustment:
sources where no -controls are required (i.e., the source
is unregulated)
sources for which control is achieved by means of an
irreversible process change that eliminates the use of
VOC or the potential for CO emissions
sources for which emissions are calculated by means of a
direct determination
For sources that are affected by a rule but are completely
uncontrolled, a RE of zero percent should be recorded in the
inventory. Sources using an irreversible process change to
control emissions should be assumed to be achieving 100 percent
RE. When emissions can be calculated by means of a direct
determination, RE falls out of the calculation and, thus, is not
applicable (i.e., the emissions estimate is not contingent on the
effectiveness of controls). For all other types of sources, RE
should be applied in a manner consistent with Section 3.
Uncontrolled Sources are exempt from application of RE. RE
does not need to be determined for sources that are completely
uncontrolled, including cases where the source is making no
attempts at compliance (illustrated by the first screening
question on the point source questionnaire (Appendix A)). In
this situation, a regulation is considered to be totally
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TABLE 2-1. SOURCE CATEGORIES COVERED BY EPA CONTROL
TECHNIQUES GUIDELINES (CTGs)
Source Category
CTG Group
Categories Predominated by Point Sources
Gasoline Loading Terminals I
Gasoline Bulk Plants I
Fixed Roof Petroleum Tanks I
Miscellaneous Refinery Sources I
Surface Coating of: I
Cans " I
Metal Coils I
Fabrics I
Paper Products I
Automobiles and Light Duty Trucks I
Metal Furniture * I
Magnet wire I
Large Appliances I
Miscellaneous Metal Farts II
Flat Wood Paneling II
Graphic Arts II
Leaks from Petroleum Refineries II
External Floating Roof Petroleum Tanks II
Gasoline Truck Leaks and Vapor Collection II
Synthetic Pharmaceutical Manufacturing II
Rubber Tire Manufacturing - II
Equipment Leaks from Natural Gas/Gasoline Processing III
Plants III
Manufacture of HOPE, PP, and PS Resins III
Fugitive Emissions from SOC, Polymer, and Resin III
Manufacturing Equipment III
Large Petroleum Dry Cleaners
SOCMI Air Oxidation Processes
Categories Predominated by Area Sources
Service Stations - Stage I I
Cutback Asphalt I
Solvent Metal Cleaning I
Commercial Dry Cleaning . II
10
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ineffective. The RE for such a source would be zero and should
be recorded as such in the base year inventory.
Irreversible Process Changes. An irreversible process change
(in the context of this guidance) involves a process modification
or equipment substitution that completely eliminates solvent use
from the production process. Irreversible process changes thus
preclude application of RE. Irreversible changes require that
the process cannot be quickly or easily reversed. Examples of
this would be substituting a hot-melt lamination process for
solvent-based adhesives and installing powder coating equipment
to replace solvent-based coatings and equipment. In general, the
use of "exempt" solvents or compliance coatings2 would not
constitute an irreversible process change. Although
incorporating these materials into the production process may
involve the installation of new equipment or the total redesign
of a production line, a total elimination of the potential VOC
use is required to be considered irreversible. (EPA recognizes
that industries may switch back to old equipment and solvent-
based coatings; State and local agencies should exercise judgment
in defining irreversibility.) Sources controlling emissions by
an irreversible process change should be assigned a RE of 100
percent in the inventory because the nature of the control
technique ensures continual compliance over time.
Direct Determination is one in which emissions are calculated
directly (e.g., explicit records for each type of coating and/or
solvent used) rather than from estimates of uncontrolled
emissions and level of control. Any calculation that involves
estimates of production rates, capture efficiency, transfer
efficiency or solvent consumption rates typically does not
qualify as a direct determination. Due to the importance of
direct determination, it is discussed in more detail below.
2.1.2 Direct Determination of Emissions
As previously stated, direct determination means that no RE
adjustment is necessary when computing base year emissions. That
is, the emission estimate is not affected by a source's
compliance or noncompliance with rules. Where an emissions
measurement is made with a high degree of certainty, RE
adjustment should not apply to that source. When reporting the RE
value for these sources, use 100 percent rather than zero or "not
applicable."3 The benefit of directly determining emissions is
that an accurate calculation of emissions is made without the
inherent uncertainties of compliance and control efficiency.
Compliance coatings include waterborne, low-solvent (high solids) and powder
coatings.
3When reporting RE for sources where a rule applies and emissions were directly
determined, report 100 percent. This reporting convention will clearly identify
to any inventory reviewers that RE was considered for the source.
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2.1.2.1 Criteria for Direct Determination of Emissions
For an emissions estimate to qualify as a direct
determination, it must meet certain criteria. First/ emissions
have to be calculated from explicit source records. Second/ no
emissions factors or assumptions (e.g./ for solvent content) can
be used in the calculation. Generally, if a control device is in
place, the estimate does NOT qualify as a direct determination.
The most common example of a direct determination of VOC
emissions is "mass balance" accounting. The data for the direct
determination must be accurate and well-documented. Each region,
state or local agency may decide what constitutes an appropriate
level of documentation for these data, consistent with EPA
guidelines stated in Section 2.1.2.4. Supporting documentation
for emissions estimates must be maintained by the State.
2.1.2.2 Example of Direct Determination
Table 2-2 shows two methods, both mass balance, that would
qualify as direct determination under the current guidelines.
Both situations imply that detailed records are available to the
source and/or the air pollution control agency.
TABLE 2-2. DIRECT DETERMINATION SCENARIOS
Process
Method
Description
Comment
Bulk
Storage/
Solvent
Use
Solvent
Use
Solvent '
Metering (mass
balance)
Accounting
(mass balance)
1)
2)
1)
2)
3)
Requires documentation by the
source
Generally applies to inks,
coatings and solvents
Requires documentation by the
source (adequate paper trail
such as purchasing records)
Assumes 100 percent
evaporation
Solvent content may be
determined by test or using
manufacturers' records
To illustrate direct determination, consider a manufacturing
facility with a product coating operation achieving compliance by
using low-solvent or waterborne coatings in lieu of control
equipment. Emissions are directly determined and calculated by
the following method:
12
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Step 1 determine coating and solvent usage over
time (e.g., a typical month during the
ozone season) from detailed plant
records;
Step 2 use manufacturer's specifications to
obtain solvent content of all coatings
used;
Step 3 for each coating used, calculate amount
of solvent used over time by multiplying
usage (gal/month) by actual solvent
content (Ibs VOC/gal coating), as
supplied by the manufacturer;
Step 4 calculate the total amount of solvent
used over time by adding the amount in
each coating and the amount of raw
solvent used for cleanup and dilution
(Ibs VOC/month);
Step 5 assume that all solvent used was emitted
to the atmosphere at some point within
the plant unless manifests indicate that
some amount was shipped offsite as waste
or the source can document that some
portion was incorporated into the
product; and
Step 6 calculate emissions in Ibs VOC/day by
dividing total solvent emitted (Ibs
VOC/month) by number of working days in
that month (days/month).
Appendix C illustrates this example in more detail.
Another example of direct determination is that estimated by
some type of continuous emission monitoring (CEM) equipment. If
used/ such equipment must be capable of determining mass balance
emissions over extended periods of time, and provisions must be
made for malfunction in the CEM equipment itself.
2.1.2.3 Major Classes of Emissions Estimation Techniques
Table 2-3 lists the major classes of emissions estimation
techniques and their potential for classification as a direct
determination. Some classes are discussed in detail, although
the salient points are contained in the table.
StacA: tests/emissions tests are generally excluded as direct
determinations because they are emissions "snapshots" rather than
an accurate assessment of emissions over time. As such, stack
tests are source-specific emission factors. However, such tests
13
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TABLE 2-3. EMISSION ESTIMATION METHODS
Method AIRS1 Applicability to Direct Determination
Code
Stack Test/
Emissions Test
CEM
Mass Balance
AP-42 Emission
Factors
Other (State)
Emission Factors
Engineering
Analysis/ Other
Methods
1
1
2
3 or
8
5 or
9
4
Stack or emissions tests represent a
"snapshot" of emissions at a single point in
time and are not considered direct
determinations . However, results of one or
more emissions tests, used in conjunction
with frequent tests of control device
performance and a complete analysis of
capture as well as control efficiency, may
be considered as a direct determination in
certain cases.
Continuous emissions monitoring (CEM) for
VOC and/or CO is theoretically possible.
CEM would preclude any RE adjustment
provided the CEM equipment is operating
properly throughout the estimation period.
Mass balance is the technique usually
considered for direct determination,
provided adequate documentation of
throughput and (VOC) content are available.
This technique generally is used for
evaporative sources. Use of estimated
control/capture/transfer efficiencies in a
calculation of emissions disqualifies the
estimate as directly determined. The effect
of regulatory or physical controls can only
be estimated from the known inputs and
outputs from the process ,
AP-42 emission factors are not direct
determinations .
Emission factors in general cannot be
considered direct determinations .
Determination based on engineering
principles or judgment cannot be direct
determination .
Aerometric Information Retrieval System
14
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maybe considered as direct determinations in conjunction with
all of the following other data:
• Records of control equipment function (efficiency and
upsets) throughout the period. These include daily
records of upsets and periodic (i.e., at least monthly)
determinations of actual efficiency and maintenance.
A detailed and applicable study of capture efficiency.
Emissions for processes that emit VOC are frequently
estimated at the building vent or control device outlet.
These estimates do not account for the control device
capture efficiency and emissions which "leak" from the
building. These losses can be very significant prior to
reaching the control device and must be factored into the
emissions estimate.
Documentation that the emissions test remains applicable
to the process and operations at the source.
* _
Mass balance is the common term for estimating emissions
based on subtracting the known outputs of the process from the
inputs to the process. This is a well—respected method for
determining emissions of SOX from combustion processes based on
sulfur inputs to the process and chemical stoichiometry. To
determine emissions for VOC, any organics incorporated in the
product plus the amount of process fugitives captured (e.g./ the
amount of recycled solvent) is subtracted from the total VOC
(typically solvent) input. No control or capture efficiency is
necessary for this calculation. The efficiency of the regulatory
or physical control is solely determined on the basis of measured
process inputs and outputs. As discussed previously, this
measurement process is restricted to documented metering or
accounting of inputs and outputs.
Emission factors are not appropriate as direct determinations
of emissions because they are not specific to the particular
source. Even with the information discussed for emissions tests
on capture efficiencies and control device operation, emission
factors will not produce an estimate sufficiently reliable to the
specific source to qualify as a direct determination.
2.1.2.4 Documenting Direct Determination
The local or State air pollution control agency is ultimately
responsible for determining the adequacy of documentation and
application of directly determined emission estimates. Local and
State agencies should maintain records necessary to document
direct determinations and should be prepared to produce this
documentation upon EPA's request. EPA is not requiring that
these records be submitted with the SIP inventory; complete
submittal of this information would unnecessarily increase the
effort of the submittal process.
15
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The following information illustrates the level of
documentation required to support direct determination of surface
coating emissions:
• Solvent (VOC) content of each coating type
• Accurate measure of the amount of each coating
• Amount of thinning and cleanup solvent
• Amount of waste solvent disposal offsite
Adequate oversight of these records by State or local
agency
Table 2-4 suggests criteria for meeting and documenting these
requirements.
2,2 OVERVIEW OF APPLICABLE APPROACHES FOR DETERMINING RE
In determining an RE value for adjusting the base-year VOC
emissions inventory, State and local agencies may elect to
(1) use an across-the-board RE presumption of 80 percent for all
sources; (2) use the questionnaire approach to determine a
category-specific RE value for both point sources and area
sources; or (3) use or design a study specific to a category in
accordance with the procedure developed by SSCD. The following
sections discuss each of these methods for determining RE.
2.3 DEFAULT VALUE APPROACH
In general, the 80 percent default RE value is used in the
absence of a local category-specific evaluation (i.e., the
questionnaire approach or the SSCD study approach). In essence,
the 80 percent default value assumes that the ability to use
control devices and existing rules to achieve a 100 percent
compliance rate is only 80 percent effective. Therefore, the
base year emissions inventory must be adjusted by this factor to
ensure that the amount of emissions reductions necessary to
achieve the CAAA-required reductions in VOC emissions can be met.
The RE value should be applied as discussed in Section 2.4,
Questionnaire Approach.
A number of surveys- were conducted to determine a
representative default RE value, one of which was conducted by
OAQPS of States in the Regional Oxidant Model Northeast Transport
(ROMNET) region. This survey indicated that regulations and
controls were approximately 80 percent effective, on average, in
achieving the target emissions reductions.
Subsequent examination of the 1989 SSCD studies have allowed
OAQPS to reexamine the 80 percent default value. The results of
the 1989 SSCD RE studies conducted by States in 7 of the 10 EPA
Regions also show an average RE value of approximately 80 percent
when averaging the results obtained from three alternate methods
(including the method contained in this guidance document) used
to calculate RE for the SSCD study. Some of the RE studies
16
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TABLE 2-4. DOCUMENTING DIRECT DETERMINATION FOR
SURFACE COATING
SOLVENT (VOC) CONTENT
Document Solvent or VOC Content of Every Coating
• Periodic Testing of Actual Coatings
• Manufacturer's Specifications for Coatings that Include
Solvents
Material Safety Data Sheets (MSDS) with Information on Total
VOC Content
• Reflect Coatings in Use during the Inventory Period
Total VOC Emitted = VOC Content x Total Coating Consumed
COATING OR SOLVENT CONSUMPTION
Record Total Coating (or Solvent) Use Regularly
Daily or Batch by Batch Basis
• Process by Process
• Coating by Coating
Use Purchasing Records if Necessary
Make Records Available during Inspections
Source May Submit Monthly or Quarterly Summaries
THINNING AND CLEANUP SOLVENT
Include Thinner and Cleanup Solvent Consumption
Daily or Batch by Batch Records
• Monthly or Quarterly Summaries
SOLVENT DISPOSAL/RECYCLE
Give Cre~ :_t for Offsite Disposal/Treatment
• ^obmit Waste Transfer Records with Information on Amounts
Shipped
ADEQUATE OVERSIGHT
Inspect Regularly
Check Facility's Summary Data against Daily Records during Inspection
Check Records (e.g., Daily Summaries) against Records Kept "on the
Floor."
Investigate and Resolve any Discrepancies
17
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indicated values in excess of 100 percent. These values are
inappropriate in reviewing inventory RE. Values greater than 100
percent imply that emissions for a category are less than
estimated. The causes of "over-compliance" (i.e., decreased
production) in these studies are already accounted for in the
inventory emissions estimates. Values greater than 100 percent
were set equal to 100 percent. The results varied from about 70
to 90 percent, depending on the selected calculation method.
It is difficult to estimate a particular category's RE for a
particular area based on a small subset of studies such as the
1989 SSCD RE studies. Where other data are unavailable to
estimate category-specific RE, the 80 percent default value is
the most appropriate based,on the information currently
available.
2.4 QUESTIONNAIRE APPROACH
The intent of the questionnaire approach is to determine a
categrory-speci.fic RE value to adjust the baseline*VOC emissions'
inventory for less than 100 percent regulatory compliance in a
nonattainment area. This approach involves the use of
questionnaires designed for both point and area sources and is
based on information on file with the source and personnel
familiar with the sources included in the study (Appendices A and
B). (Sources to be included in the process must pass a
preliminary screening test. An RE number is determined for each
category in each nonattainment area.)
2.4.1 Level of Effort
The categories representing at least 80 percent of the
emissions inventory must be surveyed with the questionnaire. The
questionnaires contain a series of generic questions covering
various factors which affect the RE determination. These factors
include the nature of the regulation, the nature of techniques
used to comply with each regulation, the performance of the
source in complying with the regulations, and the performance of
the implementing agency in enforcing the regulations. The
questionnaire is designed to be answered using only available
source file information, thus alleviating the need for source
inspections. Prior to each source evaluation/ the complete
source file information is reviewed including reports of previous
visits and inspections. Information pertaining to potential
deviations or deficiencies in State regulations must also be
reviewed prior to taking this approach. In many cases,
knowledgeable inventory staff may be able to complete the
questionnaires for a single source category in one—half day or
less.
18
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2.4.2 Procedure
The procedure involves the use of two generic questionnaires
that are based on the factors listed above and in Table 1-1. One
questionnaire is used for individual point sources (see Appendix
A) and another for area source categories (see Appendix B).
Table 2-1 listed source categories for which CTGs have been
issued and provides a good starting point for State and local
agencies to determine which questionnaire to apply.
Many States contain more than one nonattainment area, raising
the issue of whether RE should be estimated on a local or
statewide basis. In general, this procedure should be used to
determine unique RE estimates for each nonattainment area, except
in cases where statewide regulations are implemented by a single
agency throughout the State. In this case, all nonattainment
areas in the State may employ a single value. The appropriate
EPA Regional Office should be contacted for guidance if there is
any question of whether local or statewide estimates are
appropriate in a particular State.
2.4.2.1 Identifying Personnel to Perform the Evaluation
In most cases, representatives from the State or local
agency's SIP planning or inventory group and compliance group
should oversee the RE evaluations described in this document, but
this selection may vary based on the individual agency and
personnel experience. (The person conducting each evaluation
will be hereafter referred to as the "evaluator.") One of the
goals of incorporating RE in the base year inventory is to have
planning personnel become more aware of the extent to which
sources are complying with SIP regulations and the actual
emission reductions that have resulted. The evaluator should
enlist the aid of the local inspector(s) most familiar with each
source. The role of the EPA Regional Office generally will be to
review the results of the individual evaluations and/or the final
RE estimates. In specific cases where this arrangement is not
satisfactory, States or local agencies may negotiate with the
Regional Offices to modify the respective roles.
2.4.2.2 Preliminary Screening of Sources
Each point source chosen should be subjected to the
preliminary screening test at the beginning of the point source
questionnaire. This screening will determine the appropriateness
of evaluating RE by means of the questionnaire procedure for the
chosen sources. The questionnaire should NOT be used to
determine RE for the chosen source if any of the following is
true:
• the source is not regulated4
Unregulated sources which are controlled should have equipment downtime, actual
operating efficiency and process upsets factored into the emissions estimate,
although these sources are not technically subject to RE.
19
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• the source achieves emissions reduction by means of an
irreversible process change that completely eliminates
VOC from the process
• emissions from the source are calculated by means of a
direct determination
Sources for which any of the above is true should be excluded
from the Questionnaire evaluation and are exempt from the
adjustment of emissions for RE. These exclusions were discussed
in detail in Section 2.1.1.
2.4.2.3 Choosing Sources to Evaluate
State and local agencies choosing to develop category-
specific RE estimates may (1) use the questionnaire procedure for
ALL regulated stationary source categories in their inventories
or (2) use the questionnaire for 80 percent of their emissions
inventory and a combination of the default value or SSCD study
for the remainder of the emissions. If a State or local agency
wishes to use the questionnaire approach for a subset of emission
categories/ the following conditions must be met. At least
80 percent of the total pollutant-specific emissions (e.g., VOC)
must be covered by questionnaires and all categories representing
5 percent or greater of the pollutant-specific emissions must use
the questionnaire. Both conditions (80 percent coverage of total
point source pollutant emissions and every category representing
5 percent or more of the total point source pollutant emissions)
must be met for the questionnaire approach.
The most accurate way to estimate RE for point source
categories would be to evaluate all sources in each category for
which a regulation exists and average the results. Since this
would place an unreasonable burden on resources and time for the
agency performing the evaluation, agencies should evaluate RE
sources in each category for which a regulation exists according
to the following guidance. If there are ten or fewer sources in
a category, all sources should be included. If there are more
than ten, choose ten at random, complete the questionnaires and
determine if the sample size is adequate or needs to be expanded.
The point sources should be chosen randomly to avoid biasing the
results. To assure statistical accuracy, use the procedure
outlined in Appendix D for determining the sample size. (Area
sources as defined by the emission inventory will be evaluated by
category.)
One possible method for choosing random point sources is for
the evaluator to obtain a list of all sources in the local
inventory, grouped by source category. These sources should
include the numerical identification codes and any other details
necessary to obtain the appropriate file information. The
evaluator might then enlist the aid of another employee who is
unfamiliar with both the sources and the numerical coding system
of sources in the air program. This employee would be presented
20
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with a list of only the numerical identification codes, not the
company names, of all sources in the inventory grouped by source
category, and asked to randomly choose a statistically valid
sample from the necessary sources in each point source category
for which a regulation exists. Alternately, there are many
popular software packages (e.g., Lotus®) which are able to
generate random numbers with a list of sources.
2.4.2.4 Sources with Control Efficiencies Greater Than 95 Percent
Source emissions may be artificially inflated when the 80
percent default value for RE is applied to sources with stated
control efficiencies greater than 95 percent. This is of
particular concern when dispersion modeling is used. To ensure
that emissions estimates are as accurate as possible, EPA has
developed three different options to accommodate this situation.
Before selecting one of the following options, States should
attempt to verify the capture and control
efficiencies of these highly-controlled sources.
Option I:
1. Identify sources with stated control efficiencies greater
than 95 percent.
2. For these sources, apply the Questionnaire to determine the
actual RE for the source. If the Questionnaires cannot be
completed by the November 15, 1992 deadline, an adjustment
can be made afterwards.5 In these areas, Option II must be
used for the November 15, 1992 inventory submittal.
Option II:
1. Apply the 80 percent default value for RE to the sources with
control efficiencies greater than 95 percent in the base-year
inventory.
Option III:
1. Identify sources with stated control efficiencies greater
than 95 percent.
2. For the 1990 base-year inventory, use option I or II.
3. After submitting the 1990 base-year inventory, develop an
alternative questionnaire to determine RE for these highly-
controlled sources.
EPA prefers that adjustments be made prior to the public hearing on the
inventory, but no later than any other hearing held on the rate of progress plan
and attainment demonstration (see Memorandum of September 29, 1992, Public
Hearing Requirements for 1990 Base-Year Emission Inventories for Ozone and CO
Nonattainment Areas, from John Calcagni and Bill Laxton to Regional Air Division
Directors).
21
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4. Obtain EPA approval for the RE questionnaire.
5. Apply the alternative RE questionnaire to the identified
sources.
6. Adjust the base-year emission inventory after the new RE
values have been calculated for these sources.5
2.4.2.5 Answering the Questionnaires
The evaluator should complete one point source questionnaire
for each selected point source in the sample that passes the
preliminary screening test and one area .source questionnaire for
each area source category. The questionnaires are designed to be
answered using available file information only. No dedicated
source inspections are required. The complete file information
on a particular source, including reports of previous visits and
inspections, should be obtained by the evaluator prior to
answering the questionnaire. To answer the questionnaires, the
evaluator should confer with the State or local compliance
inspector most familiar with the source or soured category being
evaluated. If an answer cannot be ascertained, the space marked
"unsure" should be indicated on the questionnaire.
In addition, the evaluator should obtain any information
relating to potential deviations or deficiencies in the State or
local regulations. The most helpful information would be in the
SIP-call follow-up letter sent to the State Air Program Director
from the corresponding EPA Regional Air Division Director. This
letter delineates specific deficiencies that EPA required to be
corrected in response to the SIP-calls for nonattainment areas in
that State. Another source of information is the document,
Issues Relating to VOC Regulations, Outpoints, Deficiencies, and
Deviations, issued on May 25, 1988 by AQMD. The evaluator should
confer with the EPA Regional Office to ascertain the most current
and applicable information on regulation deficiencies.
2.4.2.6 Determination of Rule Effectiveness Values
The answers to the questions on the questionnaires each have
a point value associated with them. After answering each
question with the most appropriate response, the evaluator should
sum the point values of the answers for each section and record
the sub-totals and/or totals in the space provided on the last
page. Section 3 describes how to apply these RE values in the
emission inventory.
Determination of the RE value for point source categories has
been revised since the Post-87 RE guideline to make the category
value more representative. Formerly, a simple arithmetic average
of the questionnaire totals produced the RE value to be used for
all sources in that category (i.e., every completed questionnaire
received equal weight). The former procedure has been replaced
by a revised, emissions-weighted average to accommodate the true
effect on category emissions. By using an emissions-weighted
22
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average, the questionnaire RE value better estimates the effects
of higher (or lower) RE at large emissions sources on the overall
category emissions. Where large emissions sources have better
compliance (RE closer to 100 percent) than small emissions
sources, emissions for the category will more accurately reflect
the effect of the compliance level of the larger facilities.
The questionnaire results should be weighted by uncontrolled
emissions. This weighting system increases the overall influence
of the estimated RE at larger magnitude emitters on the category
emissions. The questionnaire results from the surveyed
facilities should be treated in the following manner:
JL Uncontrolled Emissions
RE = V [RE. * : -]
etttgory *-^ j n
2_j Uncontrolled Emissions
j-i
where: n is the number of facilities with completed
questionnaires
Table 2-5 illustrates the use of this equation and the
calculation of the RE value. The State or local agency may be
asked by the Regional Office to support RE values calculated from
the questionnaires. The State or local agency should be prepared
to document the procedures and information used to complete the
questionnaires.
2.5 SSCD STUDY APPROACH
2.5.1 Purpose of the Study
The purpose of the SSCD study is to provide the States, local
agencies and EPA with criteria and procedures for conducting an
RE study or evaluating the degree of source compliance with
existing rules. In the context of the SSCD study, RE means the
extent to which a rule actually achieves (or has the capability
of achieving) desired emission reductions, both in terms of the
reductions projected for that rule, and the reductions that would
ordinarily be achieved if the rule were properly implemented.
Like the questionnaire approach, the SSCD study only applies to
the geographic area in which it is conducted. In contrast to the
generic questionnaire approach for both point and area sources,
each SSCD study is individually designed and applied to a single
point source category.
The principal goals of the SSCD study procedure are: (1) to
determine the effectiveness of rules for a specific source
category in a specific nonattainment area according to the
quantitative criteria set forth in this protocol; and (2) to
23
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TABLE 2-5. EXAMPLE OF WEIGHTED RE VALUE USING QUESTIONNAIRE
RE Value
RE from Uncontrolled Height Weighted for
Facility Questionnaire Emissions Factor1 RE2 Facility3
A
B
C
D
E
F
G
H
I
J
100%
60%
80%
80%
85%
90%
65%
75%
95%
80%
500
100
75
200
50
30
120
35
25
60
0.42
0.08
0.06
0.17
0.04
0.03
0.10
0.03
0.02
0.05
0.42
0.05
0.05
0.13
0.04
0.02
0.07
0.02
*0.02
0.04
100%
60%
80%
80%
85%
90%
65%
75%
95%
80%
TOTAL
CATEGORY RE VALUE4
1,195
1.00
0.86
86%
1 Weight factor equals facility's uncontrolled emissions over total uncontrolled.
2 Weighted RE equals facility's RE from questionnaire times weight factor.
3 Use the RE value from the facility-specific questionnaire response for that
facility.
4 All facilities not included in the survey sample are assigned the category
value.
identify specific implementation problems which need to be
addressed by the State, local and EPA compliance and enforcement
staff in order to achieve greater RE in the future.
2.5.2 Summary of the SSCD Study Approach Procedures
The SSCD study prescribes inspections, emissions tests and
agency audits to compare actual measured emissions to "allowable"
emissions under the existing rules(s). The difference represents
the degree of compliance with the rules (i.e., the RE in
achieving emissions reductions). The study requires that the
source sample size from a single source category be determined
statistically, with considerations given to the allocation of
personnel for inspections.
The SSCD study approach consists of a two-phase study
including (1) an office investigation and (2) a field inspection
at the source. Each study initiated by a State or local agency
24
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must receive approval from the EPA Regional Office and
Headquarters. In general, the field inspection involves
determining the compliance status of a representative number of
sources in a nonattainment area through the calculation of
emissions and the determination of the percent effectiveness of
current regulations. Sources included in the study are inspected
unannounced. The elements of the field inspection include the
following: (1) rule application evaluation/ (2) State inspection
procedures evaluation, (3) compliance determinations,
(4) emissions quantification, (5) quality assurance, and
(6) inventory evaluation. An inspection checklist is developed
and used for each source. The checklist is comprised of three
sections which are (1) inventory verification, (2) regulatory
applicability, and (3) inspections procedures evaluation. All
applicable regulations and policies pertaining to the sources
under study are identified and the compliance status of the
sources with SIP rules is determined, differentiating between
procedural and emission requirements. The office investigation
phase provides a further analysis of program implementation
elements not susceptible to a comprehensive evaluation during a~
field inspection.
The study identifies problems which can be corrected,
processes corrective action options, and comments on advantages
and disadvantages of each option. Within one year following the
study, a follow-up audit is conducted to determine whether
corrective actions were implemented. Finally, the SSCD study
includes an inventory demonstration for the selected source
category which includes the following elements: (1) field
investigation follow-ups if inventory discrepancies evolve; and
(2) a search for potentially omitted sources including a survey
of source exemption applicability and a ground survey to locate
unregistered sources.
2.5.3 Calculating RE from an SSCD Study
The SSCD study approach may be applied only to a single
source category for which a given study is designed. The result
of each study is a category-specific RE estimate for a particular
geographic area and category. States and local agencies may need
to determine if previously existing SSCD study results remain
valid or if the study is outdated due to industry or regulatory
changes. Only studies deemed valid for the inventory period may
be used. To apply the result for SIP purposes, the calculation
must reflect this context.
The percentage effectiveness .calculations will be based on a
comparison of actual emissions to the allowable emissions for
sources included in the study. These emissions must be documented
as part of the field investigation phase of the study, and the
calculations must be based on emissions testing, sampling and
usage data identified for each source during the investigation.
25
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Percentage effectiveness for base year inventory applications
should be calculated according to the procedure listed below.
Compute separately the total allowable and actual emissions for
all sources on the day of the inspection or source test. The
following equation should be used:
RE Inventory Method (for SIP inventory purposes)
Baseline - Actual
Baseline - Allowable
x 100
If the baseline cannot be determined, the following equation, which
calculates the baseline from allowable emissions and the control
efficiency/ is used:
% RE =
Allowable
1 - Control Efficiency6
- Actual
Allowable
x 100
1 - Control Efficiency
- Allowable
where:
Baseline - base year inventory (before control)
Actual = emissions determined during course of study
from mass balance, stack testing, CAA
Section 114 responses, inspections and/or
production records review
Allowable = emissions determined from SIP requirements
Control Efficiency = control efficiency defined in the CTG
This method considers what emission reductions were
actually achieved and evaluates performance in terms of the
magnitude of excess emissions.
This method should be applied in any study where the
results will be used to modify the 80 percent rule
effectiveness assumption.
Users requiring more information should consult SSCD guidance
on the RE approach.
'Control Efficiency calculations are shown in Section 3.2.1.
26
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2,6 USING RESULTS FROM SSCD STUDIES, QUESTIONNAIRES AND THE
DEFAULT
The procedural approaches to determine RE using the
questionnaire and the SSCD study are vastly different.
Figure 2-1 shows a summary comparison of the questionnaire
approach (Appendices A and B) versus the SSCD study approach.
The shaded boxes represent common steps.
The State or local agency may use the questionnaire approach
or may apply the default value across the entire inventory.
Where an SSCD study result is used or all source categories are
not covered by the questionnaires, a combination of methods must
be used to complete the inventory. Table 2-6 lists the
combinations available to the State and local agencies when an
SSCD study is used or the questionnaire approach does not cover
all categories.
27
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QUESTIONNAIRE
STEP
SSCD STUDY
Ti
Perform Screening for Applicable
Sources
(Repeat Step (2) as Necessary)
Complete Questionnaire
I
Score Evaluation
,,',„'
C*t
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
Select One Point Source Category
1
Develop Appropriate Protocol/
Receive Approval from SSCD or
Region
1
1
Office Investigation
Evaluate Current Rule
Application
Field Inspections and Testing
I
Inventory Accuracy Demonstration
i
Report
Corrective Action Plan
Rule Effectiveness Value to
Apply to Base Year Emissions
for Each Category
RESULT . Rule Effectiveness Value for
One Category
• Improved Emissions Estimate by
Source
• Identification of
Noncompliance Causes
• Corrective Action Plan
Figure 2-1. Comparison of the questionnaire and SSCD study,
28
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TABLE 2-6.
COMBINING SSCD STUDY AND QUESTIONNAIRE
APPROACHES
RE Value Based on.
Approach for Other Categories
SSCD Study
Questionnaires
Other categories may be analyzed based
on questionnaires or the 80% default
value may be applied.
Remaining categories may use the 80%
default value provided the minimum
criteria for applying questionnaire
defined in Section 2.4.2.3 are met.
29
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SECTION 3
APPLICATION OF RULE EFFECTIVENESS IN BASE YEAR INVENTORIES
3.1INTRODUCTION
This section provides guidance on the application of RE to
emissions inventories and presents the emissions calculation
procedure. RE must be applied to base year SIP inventories for
ozone precursors and CO, specifically to sources of VOC, NOX and
CO. Previous SIP inventories considered only VOC and the
majority of current applications will still be for VOC sources.
(Since few emission regulations for non-mobile sources of NOX and
CO existed in 1990, RE is currently not an issue for these
pollutants for base year 1990 inventories. If these pollutants
are regulated in the future, RE will' need to be applied in
subsequent inventories.)
RE factors are to be applied for the purpose of more
accurately representing actual emissions. While iocal RE values-
may be determined on a source category basis, these same factors
should be applied in the inventory on a source-by-source basis.
Applying RE factors to individual sources will increase the
emissions indicated for most sources; therefore, it is important
for air pollution control specialists to understand that the RE
estimates determined by the above procedure are to be used for
emission inventory purposes only.
3.2 CALCULATING RULE-AFFECTED EMISSIONS
Determination of rule-affected emissions requires three
inventory data elements: (1) the RE value (percent); (2) overall
control efficiency; and (3) estimated uncontrolled emissions.
Before applying RE, the relevant sources must be identified as
described in Section 2. Once an RE percentage has been
determined for each source category and a source has been
determined to be subject to RE, the emissions from that point or
area source are adjusted. If the questionnaire approach was
used, apply the individual questionnaire RE scored for sources
surveyed by the questionnaire; apply the calculated category RE
value to the sources in the category which were not surveyed.
The calculation is done source by source at the emissions
calculation step (typically the segment or process level in the
Aerometric Information Retrieval System (AIRS) for point sources
and category by category for area sources.
The following equation is used to calculate rule-affected
emissions:
RE Emissions = Uncontrolled Emissions x (1 - ( Control Efficiency x RE ) ) .
30
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where RE and control efficiency are expressed as fractions.
equation clearly demonstrates that RE accounts for the
effectiveness of the control.
The
Section 2 discussed the derivation of the RE value. Control
efficiency and uncontrolled emissions are typical emissions
inventory elements. Uncontrolled emissions may have to be
backcalculated from the estimated controlled emissions. For
example, source tests may account for the control in place.
Control efficiency is a required SIP data element for control
devices, but control efficiency for RE includes both physical and
regulatory controls.
3.2.1 Control Efficiency
Regulatory controls are emission's limits implemented through
either regulatory or physical means. A solely regulatory control
is typically an emission rate limitation unrelated to a control
device. For example, an industrial coating operation may be
limited to using a coating of no more than 2 .0 Ibs1 VOC per gallon
coating. The control efficiency is based on the difference
between the total solvent used prior to the regulation and post-
regulation.
A physical control is a control device such as an incinerator
or carbon adsorber used to reduce emissions from a process.
Control efficiency may be reported on the basis of manufacturer's
specifications or emissions testing. To be reliable, capture
efficiency, actual operating conditions and process and/or device
upsets must be included when estimating emissions. These
variables may be factored into a single average control
efficiency or emissions may be estimated for each different
operational mode (refer to emission inventory guidance).
Application of the RE value is straightforward where the
control is a physical device (e.g., a carbon adsorber) with an
estimated efficiency (e.g., 95 percent). When the control is due
to a rule implementation (e.g., coatings restricted to no more
than 3 Ibs VOC per gallon), it is more difficult to determine the
"control efficiency" of that rule. However, there is no
distinction between regulatory and physical controls for the
purpose of applying RE.
EPA recognizes that a control efficiency inherent in a
regulation (e.g., an emission limit such as Ibs VOC per gallon
coating) may be difficult to determine. In these cases the best
option is to determine emissions before and after a regulation
was adopted from existing source records. This may be impossible
if a source was never in operation or inventoried prior to rule
adoption or if process changes have made such comparisons
meaningless. A second option is to use the control efficiency
estimate used in the development of the CTG or State/local rule.
31
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Questions have been raised regarding the control provided by
rules specifying types of storage tanks for petroleum product
storage. The best way to calculate control efficiencies for
storage tanks is to calculate emissions per unit product based on
the AP-42 equations before (e.g., a fixed-roof tank) and after
(e.g., an external floating roof tank) rule adoption. This
course may be both resource and time intensive. Representative
control efficiencies for gasolines and distillate oil from Table
3-1 may be used instead of detailed, tank-by-tank calculations.
These values have been derived based on a wide variety of tank
sizes and throughputs which indicate that emissions per unit
product from a tank type are principally dependent on the vapor
pressure of the contents, not tank size.1
TABLE 3-1. DEFAULT PETROLEUM STORAGE TANK
CONTROL EFFICIENCIES
Material
Stored
Before Rule
Condition
After Rule
Condition
Default
Control
Efficiency
Gasoline RVP7 to
RVP10
Distillate No. 2
Fixed Roof
Fixed Roof
External
Floating Roof
External
Floating Roof
95%
91%
Gasoline RVP7 to
RVP10
Distillate No. 2
•Fixed Roof
Fixed Roof
Internal
Floating Roof
Internal
Floating Roof
98%
92%
Gasoline RVP7 to
RVP10
Distillate No. 2
External
Floating Roof
External
Floating Roof
Internal
Floating Roof
Internal
Floating Roof
60%
20%
Where a regulatory or inherent control efficiency must be
determined to apply RE, the inventory preparer should consider
and use the procedures listed below to make this determination.
These procedures are listed in order of preference and
reliability:
1) Make a "before and after regulation" determination based
on historical inventory records for each affected source
or the category.
2) If (1) is not possible, refer to the local SIP
development dpcumentation that supports the planned or
expected control level anticipated from the
32
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regulations(s) applicable to the category. Use this
control level as the control efficiency for sources
covered by the rule(s).
3) As a final resort, refer to Appendix E to estimate the
expected control effectiveness for CTG categories. This
listing has been developed from CTG summaries and is only
to be used to approximate control efficiencies for RE
application where no other data are available. This
listing presents ranges in some cases; use the lower end
of the range unless other justification can be
documented. Where the upper end of the range is 100
percent, this value cannot be used except where direct
determination or irreversible process change can be
documented. EPA has not determined the validity or
reliability of these control efficiencies for this
purpose.
3.2.2 AIRS Coding
* _
The AIRS/Facility Subsystem (AFS) and the AIRS Area and
Mobile Source (AMS) are capable of storing RE values and applying
RE to the point and area source inventories, respectively. The
procedure involves setting the "SIP Rule in Place" field to "Y, "
"B," "M" or "R." These codes designate Yes, BACT, MACT and RACT,
respectively. [Note: While the field is called "SIP Rule in
Place," this refers to any rule that is in place in the inventory
area that is expected to reduce emissions, regardless of whether
or not the rule is part of the SIP.] Any source with these codes
and a nonzero control efficiency will be expected to have an RE
value. (Remember that directly determined emissions sources have
a 100 percent RE.) For emissions calculated using an emission
factor, process or throughput rate, and control efficiency, AIRS
can automatically calculate the RE emissions adjustment. Outside
the AIRS system, these calculations will have to be performed as
previously described.
When coding AIRS or other inventory transactions, all
regulated sources where the regulation has an impact on the
estimated emissions should have an RE entry in the estimated
emissions. State and local agencies should code RE values
according to the type of sources (Table 3-2):
For sources making no attempt at compliance, RE should be 0
percent
Directly determined or irreversible processes that eliminate
solvent (VOC) emissions should be coded as 100 percent
All other regulated sources should be coded with a value
between 0 and 100 percent
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TABLE 3-2. CODING RE IN ELECTRONIC INVENTORY SUBMITTALS
RE Determination
Coded RE Value
Uncontrolled Source
Irreversible Process
Change
Direct Determination
Questionnaire
0%
100%
100%
Weighted score from questionnaire
SSCD Study
Default
Study results using SIP inventory
calculation (%)
80%
3.3 DOCUMENTING RULE EFFECTIVENESS FOR THE SIP SUBMITTAL
Rule effectiveness must be documented in the SIP inventory
submittal, consistent with OAQPS Emissions Inventory
Requirements,2'^ the Quality Review Guidelines,4 and the
individual Inventory Preparation Plans (IPPs). These
requirements include a discussion of how rule effectiveness was
incorporated into the inventory. States should clearly annotate
summary emissions tables as either adjusted or unadjusted for
rule effectiveness. Emission estimates will be reviewed to
ensure appropriate application of Rule Effectiveness in the base
year inventories. Any deviations from OAQPS guidance on RE
should be discussed in the submittal.
3.4 REFERENCES
1. Memorandum from David Winkler and David Zimmerman, TRC
Environmental Corporation, to Gerri Pomerantz, Office of Air
Quality Planning and Standards, U.S. Environmental Protection
Agency, "Control Effectiveness: Petroleum Product Storage
Tanks." August 13, 1992.
2. U.S. Environmental Protection Agency, Emission Inventory
Requirements for Ozone State Implementation Plans, EPA-450/4-
91-010, Office of Air Quality Planning and Standards,
Research Triangle Park, NC, March 1991.
3. U.S. Environmental Protection Agency, Emission Inventory
Requirements for Carbon Monoxide State Implementation Plans,
EPA-450/4-91-011, Office of Air Quality Planning and
Standards, Research Triangle Park, NC, March 1991.
34
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4. U.S. Environmental Protection Agency, Quality .Review
Guidelines for 1990 Base Year Emission Inventories, EPA-
454/R-92-007, Office of Air Quality Planning and Standards,
Research Triangle Park, NC, August 1992.
35
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SECTION 4
EXAMPLE CALCULATIONS
The following examples illustrate how to include RE in the
emissions calculations for several types of facilities. Most of
these examples are presented on a daily emissions basis.
Typically/ emissions are first calculated on an annual basis. RE
actually applies to both annual and daily estimates; EPA emission
inventory guidance discusses the calculation of daily estimates
from annual estimates.
4.1 POINT SOURCES
4.1.1 Bulk Terminals (Loading Racks)
Calculation based on a device control efficiency and RE
questionnaire results.
A petroleum products bulk terminal distributes motor gasoline
and distillate fuels (heating oils, etc.). In 1990, the facility
distributed 110,000,000 gallons of gasoline and 54,000,000
gallons of distillate fuels. The loading racks used to transfer ,
the fuels use refrigerated vapor recovery units (RVUs) to control
emissions. The control efficiency for RVUs is greater than 90
percent as determined by an approved EPA method. The equipment
is checked annually unless obvious problems require earlier
inspections, and records of all repairs are maintained for agency
review. The facility is inspected triennially, with the most
recent inspection occurring 3 years ago. Emission factors for
gasoline and distillate fuel loading loss have been determined to
be 8.5 and 0.02 pounds VOC per thousand gallons, respectively. A
questionnaire was completed for this facility and a RE of 78
percent was estimated for this facility (overall 82 percent for
the category). What emissions should be reported for this
facility?
Answer: Compute the loading losses for gasoline and distillate.
Emissions are based on emission factors and therefore
must include RE. Use the facility-specific RE rather
than the category estimate.
Base Data for Loading Losses
Gasoline Distillate
Throughput
(gallons)
Emission Factor
Control Efficiency
(AP-42)
Rule Effectiveness
110,000,000
8.5 Ibs VOC/103 gal
>90%
78%
54,000,000
0.02 Ibs VOC/103 gal
>90%
78%
36
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Emissions = Emission Factor Activity Level
x (1 - (Control Efficiency x RE))
A. Gasoline Loading Losses
Emissions - 8.5 Ibs VOC/1Q3 gal x 110,000,000 gal x (1 - (0.90 x 0.78))
= 278,630 Ibs VOC
B. Distillate Fuel Loading Losses
Emissions = 0.02 Ibs VOC/103 gal x 54,000,000 gal x (1 - (0.90 x 0.78))
= 321.8 Ibs VOC
C. Total Emissions (from Loading Losses)
Total Emissions = Gasoline Emissions + Distillate Emissions
= 278,630 + 321.8 Ibs VOC
= 278,952 Ibs VOC
= 139 tons VOC
4.1.2 Beverage Can Coating
Calculation based on an effective control efficiency in
the absence of a control device, solids equivalency
determination and RE questionnaire results.
A beverage can coater has been required to use high-solids
coatings for its interior can coating. The plant personnel
follow a weekly maintenance routine. The facility was last
inspected in June for compliance evaluation, with the last
previous inspection occurring three years ago. The following
coating and process characteristics have been determined.
The coater previously used 50 gallons per day of interior can
coating. The coating had a density of 9 pounds per gallon. The
coating was 60 percent solvent (by weight); the solvent was 100
percent VOC with a density of 8 pounds per gallon. The coater is
required to use a new coating that does not exceed 3 pounds of
VOC per gallon of coating. The manufacturer reports a density of
10 pounds of coating per gallon of reformulated coating. No
change in production volume of coated cans has occurred, but the
coating consumption (in gallons per day) is not reported in this
year's inventory. This facility was not included among the
questionnaires, but the category average RE is 84 percent. What
emissions should be reported in the inventory?
Answer: In most categories, control efficiencies and RE are
applied to uncontrolled plant emissions resulting in RE
emissions. Since the end result of coating is the
application of the solid fraction of the coating, control
efficiencies for coatings are calculated as the reduction
37
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in emissions related to the coating solids only. Thus,
the first step in estimating the control efficiency for
this example is to estimate VOC emissions per volume of
solids.
Old Coating
Solve/it Volume Fraction = Coating Density x
Solvent Height Fraction
Solvent Density
(9 Ibs of coating/gal coating) x (0.60 Ibs solvent/Ibs coating)
8 Ibs solvent/gal coating
= 67.5%
Solids Required = Coating Consumption x (I - Solvent Volume Fraction)
= (50 gal coating/day) x (1 - 0.675)
= 16.25 gal solids/day
Emissions * Coating Consumption x Solvent Volume Fraction x Solvent Density
x Solvent VOC Fraction
= 50 gal coating/day x 0.675 gal solvent/gal coating x 8 Ibs solvent/gal solvent
x 1.00 Ibs VOC/Ibs solvent
=270 Ibs VOC/day
Emissions per Volume Solid
VOC Emissions
Solids Required
= 270 Ibs VOC/day
16.25 gal Solids/day
= 16.6 Ibs VOC/gal Solids
New Coating
„ , VOC Content of Coating
Solvent Volume Content =
Solvent Density
= 3 Ibs VOC/gal Coating
8 Ibs VOC/gal Solvent
= 0.375 gal Solvent/gal Coating
= 37.5%
38
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Solids Volume Content = 1 - Solvent Content of Coating
= 1 - 0.375
= 0.625 gal Solids/gal Coating
- 62.5%
Coating Required
Solids Required
Solids Volume Concent
16.25 gal Solids/day
^.625 gal Solids/gal Coating
26.0 gal Coating/day
Emissions = Coating Required Solvent (VOC) Content of Coating
= 26.0 gal Coating/day 3 Ibs VOC/gal Coating
=78.0 Ibs VOC/day
Emissions per Volume Solids
Emissions
Required Solids
78.0 Ibs VOC/day
16.25 gal Solids/day
=4.80 Ibs VOC/gal Solids
Now that the emissions rates per gallon of solids have been
determined, the control efficiency and emissions may be
determined.
Control Efficiency - (1 -
Controlled (New Coating) Emissions per Volume of Solids
Uncontrolled (Old Coating) Emissions per Volume of Solids
4.80 Ibs VOC/gal Solids
16.6 Ibs VOC/gal Solids
71.1%
Emissions = Solids Required x Uncontrolled VOC/gal Solids x
(1 - (Control Efficiency x RE) )
= 16.25 gal Solids/day x 16.6 Ibs VOC/gal Solids x {1- (0.711 x 0.84))
= 109 Ibs VOC/day
(This is an illustrative case. In an actual
inventory, emissions from the exterior coating
would also be calculated.)
39
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4.1.3 Paper Coating Facility
Calculation based on direct determination of emissions.
A paper coater uses only coatings specified by the
manufacturer to contain 2.9 pounds VOC per gallons, less water,
to comply with the RACT limit. Coating usage at the plant is
documented to be 100 gallons, less water, per day and no
additional solvents are used. This information was confirmed
during the annual inspection. The RE for this source category
has been determined to be 70 percent based on the RACT reduction
calculated for the category. What emissions should be reported
in the inventory?
Answer: Emissions from this plant can be calculated by means of a
direct determination, because the solvent concentration
is determined based on the manufacturer's specification
and the coating use is documented daily, thus RE does not
need to be applied.
» ._
Emissions = VOC content of coating x Coating usage
= 2.9 Ibs VQC/gal coating less water x 100 gal coating less water/day
=290 Ibs VOC/day
4.1.4 Metal Furniture Coating
Calculation based on transfer and control efficiencies
and the default RE value.
A large metal furniture manufacturer applied 326 gallons of
coating solids on its furniture each day (i.e., it actually
sprays more, but only 326 gallons of solids are actually
deposited the products). The coating it uses contains 35
percent by volume solids (65 percent VOC). The solvent used
weighs 7.33 pounds per gallon. The facility uses high-volume,
low-pressure (HVLP) spray equipment to achieve an 85 percent
transfer efficiency (TE). The facility has also installed RACT
to achieve an estimated 82 percent emissions reduction. The
default RE has been applied to this source category (80 percent)
What emissions should be reported in the inventory?
Answer: Uncontrolled emissions should be determined by
calculating the amount of coating solids applied and the
amount of coating applied. Controlled emissions are
based on the RACT emissions reduction and the default RE.
40
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, ,,_, _, 326 ?ai solids/day
Total solids sprayed = = 384 gal solids/day
0.85 TE
gal solids/day
Total coating applied =
384 gal sol ids/day
% solids 0.35 gal solids/gal coating
= 1,096 gal coating/day
,,_,„, .
Uncontrolled Emissions
coating Ibs VOC
x % solvent x ..
gal VOC
day
Uncontrolled Emissions = (1,096 gal coating/day) (0.65) (7.33 Ifcs VOC/gal VOC)
"= 5,227 Jis VOC/day
Emissions = Uncontrolled Emissions x Ci - (Control Efficiency x RE))
Ibs VOC
= 5,227 x (1 - (0.82) (0.80))
1,798
day
Ibs VOC
day
4.1.5 Automobile Assembly Plant:
Calculation based on a device control efficiency, and
solvent-use recordkeeping and RE questionnaire results.
An assembly plant that coats automobile parts uses 150
gallons per day of coatings containing 5.5 pounds VOC per gallon.
An additional 10 gallons of solvent, with a density of 7.1 pounds
VOC per gallon, is used for cleanup each day. Emissions are
controlled by a carbon adsorber that demonstrated a 90 percent
capture and control efficiency during a recent test. The plant
keeps substantial records of coating and solvent usage, but no
data on control device operation and/or maintenance (O&M). The
RE for this source category has been determined to be 75 percent
based on questionnaire responses. What emissions should be
reported in the inventory?
Answer: It may appear that emissions can be calculated by means
of a direct determination due to the good coating and
solvent records at the source. However, the presence of
41
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a control device precludes direct determination of
emissions. Therefore/ RE needs to be included in the
emissions calculation.
Uncontrolled Emissions = {150 gal Coating/day x 5.5 Ibs VOC/gal Coating)
+ (10 gal Solvent/ day x 7.1 Ibs VOC/gal Solvent)
= 825 Ibs VOC/day + 71 Ibs VOC/day
= 896 Ibs VOC/day
Emissions = Uncontrolled Emissions x (I - (Control Efficiency x RE) )
= 896 Ibs VOC/day x (1 - (0.90) (0.75) )
= 291 Ibs VOC/day ,
4.1.6 Large Appliance Coating
Calculation based on an irreversible process change and
direct determination of emissions.
An appliance manufacturer uses 1,200 pounds of a powder
coating per day. The coating is applied with electrostatic spray
equipment achieving a transfer efficiency of 95 percent. The
company also uses 10 gallons of solvent with a density of
7.1 pounds VOC per gallon solvent for daily cleanup operations.
The plant keeps detailed records of coating and solvent use. The
RE for this source category has been determined to be 75 percent.
What emissions should be reported in the inventory?
Answer: Powder coating is an irreversible process change, but the
cleanup solvent emissions must be calculated.7 Since
there are no controls for the cleanup solvent, but
adequate records are kept, a direct determination of
emissions can be made:
Emissions = (7.1 Ibs VOC/gal x 10 gal/day)
=71 Ibs VOC/day
Powder coating may not always be an irreversible change; the state or local
agency should make this determination.
42
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4.1.7 Large Petroleum Dry Cleaner
Calculation based on the expected rule control
efficiency, reported controlled emission and the default
RE value.
A large petroleum dry cleaner has an estimated controlled
emission rate of 200 tons of VOC per year. The RACT control
level is 80 percent based on analysis of the rule for the
nonattainment area. The plant is in operation 310 days per year,
All inventory categories have been assigned the 80 percent
default RZ value. What emissions should be reported in the
inventory?
Answer: Emissions should be calculated as follows:
Controlled Emissions
Uncontrolled Emissions =
(1-Control Efficiency)
200 tons VOC/year
(1-0.8)
= 1,000 tons VOC/year
Daily Emissions = Uncontrolled emissions x (1 - (Control Efficiency x RE))
1,000 tons VOC/yr x 2,000 Ibs/ton
310 days/yr
- 2,322 IBS VOC/day
x (1 - (0.80)(0.80))
4.1.8 Graphic Arts
Calculation based on multiple sources at one facility,
with and without controls.
A printing manufacturer uses two gravure lines at a given
facility. The first gravure line (line 1) was uncontrolled in
1990 and did not comply with SIP rules at that time; the second
gravure line was controlled by a fume incinerator meeting the
State SIP rule. (Line 1 was subsequently upgraded in 1991 to
include fume incineration). Plant personnel are required to
complete a formal training program on operation and maintenance
and follow maintenance guidelines daily. The facility was found
out of compliance during the past year due to incineration
failure but was back in compliance within 72 hours. A violation
notice was placed into the State Agency files. The facility is
inspected annually. The device control efficiency for fume
incineration was determined to be 95 percent during the previous
compliance test. Following a survey using the questionnaire, RE
for graphic arts was calculated to be 85 percent.
43
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For line process, 25,000.pounds of ink (12 percent VOC by
weight) were used. Other solvents used for viscosity adjustment
and cleaning totalled 100/000 pounds (100 percent VOC). A total
of 900,000 pounds of ink (60 percent VOC by weight) were used in
line 2, while 600,000 pounds of other materials (100 percent of
VOC) were used for Line 2. The ink consumption is tracked daily
at the press and the VOC content is given by the manufacturer.
What are the annual emissions from this facility with Rule
Effectiveness?
Answer: The two gravure lines must be treated separately. Line 1
had no controls and RE zero because there was no attempt
at compliance. The second gravure process (Line 2) is
controlled and RE must be applied. For comparison,
facility emissions with and without RE are presented.
A. Line 1 Gravure Process (No Controls)
Emissions = Ink Emissions •»• Other Emissions
* _
1. Ink Emissions:
Ink Emissions = Ink Consumed x Ink VOC Fraction
= 25,000 Ibs Ink x 0.12 Ibs VOC/lbs ink
= 3,000 Ibs VOC
2. Emissions for Other Solvents:
Other Solvent Emissions = Other Solvents Consumed x Other Solvent VOC Fraction
= 100,000 Ibs Other Solvents x 1.00 Ibs VOC/lbs Other Solvents
= 100,000 Ibs VOC
3. Line 1 Emissions:
Emissions = Ink Emissions + Other Solvent Emissions
= 3,000 Ibs VOC + 100,000 Ibs VOC
= 103,000 Ibs VOC
=51.5 cons 700
B. Line 2 Gravure Process
Step 1 - Before Rule Effectiveness
Emissions = (Ink Emissions + Other Solvent Emissions) x (1 - Control Efficiency)
1. Ink Emissions:
Ink Emissions = Ink Consumed x Ink VOC Fraction
= 900,000 Ibs Ink x 0.60 Ibs VOC/lbs Ink
= 540,000 Ibs VOC
44
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2. Emissions from Other Solvents:
Other Solvent Emissions - Other Solvents Consumed x Other Solvent VOC Fraction
= 600,000 Ibs Solvent x 1.00 Ibs VOC/Ibs Other Solvents
= 600,000 Ibs VOC
3. Line 2 Emissions (Before Rule Effectiveness)
Emissions = {Ink Emissions + Other Solvent Emissions) x (1 - Control Efficiency)
= (540,000 Ibs VOC + 600,000 Ibs VOC) x (1 - 0.95)
= 57,000 Ibs VOC
=28.5 tons VOC
Gravure Process (Emissions Accounting for RE)
RE Emissions = (Ink Emissions + Other Solvent Emissions) x
(1 - (Control Efficiency x RE) )
= (540,000 Ibs VOC + 600,000 Ibs VOC) x (1 - (0-. 95 x 0.85) )
= 219,450 Ibs VOC
= 109.7 tons VOC
C. Facility Emissions
Facility Emissions = Line 1 Emissions * Line 2 RE Emissions
=51.5 + 109.7 tons VOC
* 161.2 tons VOC
4.2 AREA SOURCES
4.2.1 Stage I (Area Source Category)
Calculation based on rule penetration and SSCD study
results.
The gasoline throughput for service stations in a
nonattainment area is reported to be 400,000 gallons gasoline per
day. The uncontrolled Stage I emissions are estimated to be 11.5
pounds VOC per 1,000 gallons. The State regulation requires 95
percent control at each facility and covers about 90 percent of
the overall emissions from the category (i.e., rule penetration =
90 percent). The RE for this category has been determined to be
60 percent following an SSCD study conducted by the State agency.
What emissions should be reported .in the inventory?
Answer: RE and penetration should be introduced into the
emissions calculation as follows:
45
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Uncontrolled emissions = 400,000 gal gasoline/day x 11.5 Ibs VOC/l, 000 -gal gasoline
= 4,600 Ibs VOC/day
RE Emissions = Uncontrolled emissions x (1 - (Control Efficiency x RE x Rule Penetration) )
= 4,600 Ibs VOC/day x (1 - (0.95)(O.SO)(0.90))
= 2,240 Ibs VOC/day
4.2.2 Architectural Coating (Area Source Category)
Calculation based on direct determination of emissions.
The ozone nonattainment area inventory includes architectural
surface coating as an area source category. Architectural
coatings include surface coating, painting and decorating of
architectural structures using water-based and oil-based
coatings, cleanup solvents and thinners. The agency describes _
the following inventory method and emissions data for the
category.
Architectural surface coating use (consumption) in the
nonattainment area is based on a comprehensive survey of all
coating manufacturers and marketers in the nonattainment area.
The survey results provided consumption of each type of
coating/solvent/thinner and the manufacturers' statement of its
solvent content. The survey results are- from 1990 and include
all coatings, thinners and solvents used in the category.
Results are an annual weighted composite VOC emission expressed
as pounds VOC per gallon coating (0.46 pounds VOC per gallon) and
an estimate of 1,555,322 gallons of coating used in the
nonattainment area. What emissions should be reported in the
base year inventory and what RE value should be applied?
Answer: Although applied to an area source category, this example
follows the traditional point source interpretation of
direct determination because it provides (1) an
accounting of consumption and (2) use of a known solvent
content. However, the inventory procedures are entirely
different for area source categories. In this example/ a
direct determination is based on the mass balance done
for the nonattainment area.
Emissions * (0.46 Ibs VOC/gal) x (1,555,322 gal)
= 715,448 Ibs VOC/year
=358 tons VOC/year
46
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APPENDIX A
RULE EFFECTIVENESS QUESTIONNAIRE
POINT SOURCES
-------
-------
RULE EFFECTIVENESS EVALUATION FORM
Point Sources
Source Category
Source Name
Source Location
Source Identifier
Choose the one most appropriate response for each question.
Answers should be confirmed by information in the State or local
agency's files. When the questionnaire has been completed, tocal
the scores to determine RE for the source; the average score for
all evaluated sources in a category is the RE for that category.
Preliminary Screening:
1. Is this source currently uncontrolled?
No
Yes
(If "yes" t choose another source to evaluate, and indicate a RE
of 0 percent for this source in the inventory.) '
Are emissions from this source controlled No
by an irreversible process change? Yes
(If "yes", choose another source to evaluate, and indicate a RE
of 100 percent for this source in the inventory.)
Have emissions from this source been.
calculated by means of a direct determination?
No
"Yes
'.If "yes", choose another source to evaluate, do not apply RE
to this source, and indicate a RE of 100 percent in the
inventory.) l
Nature of the Regulation
1. Does the regulation contain uncorrected deficiencies (not
including record keeping deficiency) as specified in the
SIP-call follow-up letter from the EPA Regional Air
Division Director to your State Air Program Director?
No (5:
Yes or unsure (0}
Score
If a source's emissions have been estimated using direct determination, maintain the supporting data and
calculations in your files.
A-2
-------
Does the State require source to keep records sufficient to
enable an inspector to determine compliance status?
Yes
No or unsure
0)
Score
How complex is the determination of compliance? (If State
can verify through detailed records that all necessary-
compliance determination procedures have been carried out,
score 5 points for this question regardless of answer
checked below.)
Determination can be made by looking at
facility, as in the case of an equipment
standard.
Determination can be made by collecting
and analyzing one sample or by evaluating
continuous emission monitoring reports.
Stack testing, including capture and *
control, must be performed to determine
compliance.
Determination requires that multiple
samples be taken and analyzed and that
plant records be evaluated, as in the case
of cross-line averaging, time averaging,
or other bubbles.
Score
(2
B. Nature of Procedures__Used to Comply With Regulation
1. This question concerns the relative level of confidence in
the long-term performance capabilities intrinsic to
different control techniques (e.g., how time in operation
and maintenance degradation might affect emissions
control) . (Check each technique used at the facility,
total the scores assigned to each control, divide by the
number of controls and report the average as a single
score. If State can verify through detailed records that
zhe source has actually been in continuous compliance at
all times during the past two years, score 10 points on
this question regardless of control methods used.)
[e.g., coating
Floating roof
Thermal incinerator
Vapor balance
Reversible process change
reformulation)
Condensation system
Carbon adsorber
Catalytic incinerator
Other (assign point value <_ 10, as
appropriate, relative to above controls!
(8)
(8)
(8)
(7)
(7)
(7)
Score
A-3
-------
2. Are fugitive emissions that might cause noncompliance a
possibility where add-on controls are used (cheese one)?
. No or not applicable because
there is no add-on equipment (5)
No, because they have been shown by
an EPA-approved capture efficiency
test to be below allowable limits and
to be so on a continual basis (5)
Yes or unsure (0)
Score
C. Performance of Source in .'.''jprnplying. With .Regulation
1. What procedures dc-:-1
maintenance (O&M) .i
•rhe source follow for operation and
che control equipment (check one)?
Plant personnel complete a formal
training program and follow daily
written instructions for O&M
Same as above, except no training
Plant personnel follow weekly
established OiM routine
Equipment is assumed to be operating
correctly unless major malfunction
is detected
(5:
(4!
(3
(i:
Score
What is the nature of self-monitoring efforts conducted by
the plant to assess compliance (check one}?
Source test (using EPA-approved
method) -1 is conducted annually
Sample analysis (using EPA-approved
method) -' is conducted for each ink
or coating used
Above tests are performed, but
less frequently
None or unsure
;3
;o
Score
Does the plant keep records of data (including self-
monitoring, O&M, coating usage, etc.! that would allow
verification of compliance?
Yes .
No or unsure
Score
^or examples of approved test methods, see "Test Methods or Procedures for Group I, II, and III CTG's," Issues
Relating to VQC Regulations. Cutpoims. Deficicndi's. and Deviations. EPA/OAQPS/AQMD/OCMPB/PIS, May 25,
1988.
•'Ibid.
A-4
-------
4a. Has source been found to be out of compliance in the last
12 months? (If "yes", then answer question 4b; otherwise,
skip to Part D)
No
Yes or unsure
(0)
Score
4b. In responding to Notices of Violation, did the source
demonstrate compliance within the required time frame?
(Answer this question only if you answered "yes" to
question 4a. above)
Yes
No or unsure
5
0
Score
D . Performance of Implementing Agency in Enforcing Regulation
1. Please answer the following questions regarding
verification of the source's compliance? .,
a.
c.
Are all permits and abatement orders
available? • _ No (0)
_ Yes or not applicable (2)
Score _
Are all applicable requirements identified
in the permit (e.g., emission limits,
averaging times, compliance schedule,
monitoring, recordkeeping, reporting,
operation and maintenance, test
requirements)?
No (0)
Yes or not applicable (2)
Score
Are accurate and complete flow diagrams
available for the emission points and
control, capture, ventilation and process
systems? . _^ No (0
Yes or not applicable (2
Score
Are all source test and sample analysis
results available?
No (0)
Yes or not applicable (2)
Score
Are all appropriate control system
operating data available? No
Yes or not applicable (2)
Score
Total Score '
A-5
-------
2 . What is the professional background of the person who most
frequently inspects 'this source? (Choose the one most
applicable answer with highest score.)
Has >_ 3 years of experience in
conducting plant inspections (5)
Has engineering degree and has completed
formal training program on how to
conduct plant inspections (4)
Has engineering degree (3)
Has completed formal training program
on how to conduct plant inspections (3)
No training, < 3 years of experience,
and no engineering degree (0)
Unsure (0)
Score
3 . How many times has source been inspected in the past 24
months? (Inspections must be confirmed by inspection
reports in implementing Agency's file.}
>2 times, unannounced , (10)
Once or twice, unannounced (8)
Once or more, with prior notice or unknown
if notice given (6)
None or unsure (0)
Score
4. What was the highest level of inspection performed at the
source in the- last 24 months? (This must be confirmed by
inspection reports in the implementing agency's file.)
Level 4: sampling inspection including
preplanned sample collection (5)
Level 3: compliance evaluation (4)
Level 2: walk-through (2)
Level 1: observation from outside (1)
None or unsure (0)
Score
5. Does the agency generally determine compliance by the
method(s) specified in the regulation?
Yes (5)
No or unsure (0)
Score
6. If this source has been found out of compliance within the
last 12 months, has formal documented enforcement action
(e.g., consent decrees, variances, court actions,
penalties) been taken against the source?
Not applicable because source has not'
been found out of compliance (5)
Yes (5)
No or unsure (0)
Score
A-6
-------
7. If source has been found out of compliance within the last
12 months, has a follow up inspection been made to affirm
compliance?
Not applicable because source has not
been . found out of compliance
Yes
No or unsure
5)
0)
Score
SCORING:
A: of 15
TOTAL SCORE =
B:
of 15
C:
of 25
D:
Of "45
of 100 points maximum = RE value for source
A-7
-------
APPENDIX B
RULE EFFECTIVENESS QUESTIONNAIRE
AREA SOURCE CATEGORIES
-------
-------
RULE EFFECTIVENESS EVALUATION FORM
Area Source Categories
Source Category
Location
Choose the one.most appropriate response for each question.
Answers should be confirmed by information in the State or local
agency's files. When the questionnaire has been completed, total
the scores to determine RE for the category.
1.
Does the regulation contain uncorrected deficiencies as
specified in the SIP-call follow-up letter from the EPA
Regional Air Division Director to the State Air Program
Director?
No
Yes or unsure
(5)
(0)
Score
2.
What has been the nature and extent of source education on
requirements of the regulation? (Check all that apply and
sum scores.)
Individual source mailings on compliance
requirements (7)
Educational opportunities for
plant personnel (7)
General notices in newspapers, trade
journals, etc. (3)
Inform trade association (3)
None (0)
Score
3. What percentage of sources in the inventory typically are
spot checked annually (c-hecJc one) ?
>30 percent (20)
10-30 percent (15)
5-9 percent (10)
1-4 percent (5)
<1 percent or don't know (0)
Score
B-2
-------
What percentage of the past year's spot checks indicated
compliance (check one) ?
100 percent
90-99 percent
50-89 percent
25-49 percent
1-24 percent
<1 percent or don't know
Not applicable since no spot checks
were done
Score
(30)
(25).
(20)
(10)
(5)
(0)
(0)
Has formal documented enforcement action been taken against
sources found to be out of compliance (check one) ?
Not applicable since no inspected
sources have been found to be out
of compliance
Yes, for all noncomplying
sources
Yes/ in 50 to 99 percent of the cases
Yes/ in < 50 percent of the cases
Never/ or don't know
(10)
(10)
(5)
(2)
(0)
Score
Have enforcement actions for sources in this source category
been publicized in the media (newspaper, TV, radio, trade
journals)/ either through news stories or paid advertisements
(check one) ?
Not applicable since no inspected sources
have been found to be out of compliance
Yes, in every case
Yes, in 50 to 99 percent of the cases
Yes, in < 50 percent of the cases
Never, or don't know
(5)
(5)
(3)
(1)
(0)
Score
Have follow-up inspections been made on sources which were
found to be out of compliance (check one) ?
Not applicable since no inspected sources
have been found to be out of compliance
Yes, in 100 percent of the cases
Yes, in 50 to 99 percent of the cases
Yes, in < 50 percent of the cases
Never, or don't know
(10)
(10)
(5)
(2)
(0)
Score
TOTAL SCORE:
(100 points maximum)
= RE for Area Source Category
B-3
-------
APPENDIX C
DIRECT DETERMINATION EXAMPLE
-------
-------
DIRECT DETERMINATION EXAMPLE
The following wood furniture coating scenario illustrates
typical emission inventory information that may be collected in
the surface coating category. This type of information is used
to'make and support a direct determination of emissions for an
ozone base year SIP inventory.
FACILITY:
DESCRIPTION
RITEWAY FURNITURE
100 Commerce Drive
Ozoneville, USA
Riteway Furniture fabricates arid paints oak furniture. The
plant uses high VOC stains, lacquers, glazes and sealers. This
source is covered under the State's applicable RACT rules for
wood furniture surface coating. Some of their lines have already
been converted to high volume, low pressure (HVLP*) spray guns. ~
On average, their coatings range from 5.67 Ibs VOC/gallon coating
to 6.2 Ibs VOC/gallon coating. The State air agency has
recommended that other lines be converted to HVLP spray guns and
that average coating solvent content be capped at 6.0 Ibs VOC
(monthly average) for their forthcoming permit amendment.
EMISSION SOURCES
POINT
SB-1
SB-2
SB-3
SB-4
SB-5
ADDITIONAL INFORMATION
PROCESS
Paint Spray Booth
1990
CONTROL DEVICE
None
None
None
None
None
THROUGHPUT
(see attached
sheets)
The facility summarizes and submits monthly summary data to
the State. Coating and solvent usage (including thinners and
cleanup) are tracked as used at the booths, but the spray booths
are not counted separately. The facility was inspected in 1990
and the monthly summaries were consistent with their daily
records on file at the plant, according to the State compliance
enforcement.
The attached sheet is a monthly spreadsheet from Riteway; all
twelve are on file at the State agency. The "LBS VOC/GAL" come
from manufacturer's specifications for the coatings.
C-2
-------
ANSWER: There is sufficient information for direct determination
of emissions because the amount of each coating and
thinner/cleanup solvent used is tracked and documented
regularly for each coating/solvent/ the VOC content of
these coatings has been provided by the manufacturer and
the amount emitted is a mass balance calculation based on
these data. In this instance/ 100% emission has been
assumed. The facility would be expected to document any
claims that less than 100% is emitted (e.g., some VOC is
incorporated into the product.)
C-3
-------
RITEWAY FURNITURE: JANUARY 1990 EMISSION REPORT
MFC NUMBER
S3-4100
S7-4057
PSA7-2460
Pl-3262
PC3-888
PC7-935
PC8-870
LS-1582
LS-1728
PC-1006
T-636
WS-2196
WS5-3503
WS7-2S89
WS7-3303
WS7-3465
F-2679
CA-175
F-2554
F-2672
LE2-3229
07-1189
08-1190
PF7-2251
T-17Q3
T-1743
T-1665
T-1769
T-164B
T-1647
T-1529
T-1605
T-1S22
UV-505
DESCRIPTION
ENGLISH SAP STAIN
ANTIQUE ASH SAP STAIN
OAK/KORN IND.
WHITE PRIMER
ANTIQUE TONER
ENGLISH TONER
BLUE TONER
LACQUER SEALER
WASHCOAT
PENETRATING WOOD SEAL
MAX
CLEAR GLAZE
ASH WIPING STAIN
ANTIQUE GLAZE
OAK/KORN IND.
ENGLISH GLAZE
50 SHEEN CAT/LACQUER
CATALYST
60 SHEEN M/R LACQUER
60 SHEEN M/R LACQUER
WHITE LACQUER
E/G SHADE
BLUE SHADE
WATER BASE PUTTY
GLAZE REDUCER HYSOL 10
GLAZE REDUCER HYSOL 15
50/50 CUT HYSOL 10/15
MINERAL SPIRITS
LACQUER THINNER
WA5HOFF THINNER
LACQUER RETARDER
NCR STAIN REDUCER
VMSP NAPTHA
STRIPCOAT
A
LBS/
GAL
6.82
6.62
7.35
8.26
6.83
6. 93
7.73
.7.38
7.10
7.10
6.81
7.62
7.58
8.74
8.92
8.57
7.86
8.24
7,54
7.92
8.27
7.04
7.10
11.98
7.27
7.42
7,35
6.42
6.63
6.61
7.91
6.63
6.23
7.81
B
LBS VOC/ GAL
(less water)
6.81
6.61
7.03
6.02
6.53
6.53
6.41
6.05
6.51
6.51
6.81 ,
4.28
4.98
3.88
3.64
3.98
5.39
4.12
5.88
5.16
5.82
6.81
6.61
0.00
7.27
7.42
7.35
6.42
6.63
6.61
7.91
6.63
6.23
5.69
C
GAL
USED
0.00
56.00
0.00
190.0
0
90.00
10.00
65.00
92.00
30.00
0.00
0,00
20.00
15.00
55.00
S.OO
25.00
0.00
0.00
0.00
320.0
0
35.00
0.00
11.00
6.00
0.00
0.00
130.0
0
0.00
105.0
0
15.00
SS.OO
1,330
B*C
LBS VOC
EMITTED
0
370
0
1,144
588
65
417
557
19S
0
0
86
75
213
18
100
0
0
0
1,651
204
0
73
0
0
0
956
0
696
0
119
0
343
0
7,867
C-4
-------
ADDITIONAL QUESTIONS ON DIRECT DETERMINATION
Do the following examples constitute direct determination?
1. The facility used the RACT level (6.0 Ibs VOC) to calculate
emissions.
No, an assumed content cannot qualify as a direct
determination.
2. The facility used the RACT level to estimate one coating
line.
Four lines could be directly determined, but the single line
could not be treated as a direct determination.
3. The facility reported an annual mass balance, but daily
records were not available during the inspection.
The record unavailability would fail the reporting
requirements for direct determination.
4. The facility collected waste coating and shipped it offsite
as hazardous waste.
Yes, direct determination could be claimed if the manifests
are on file and the solvent portion is quantified. Yes, if
this waste is not quantified, but no "credit" is given for
the waste. No, if this waste is not documented but is
subtracted from the emissions.
5. For the inventory year, this source was not permitted under
the regulation.
This fact has no bearing on direct determination, only the
application of Rule Effectiveness.
6. The facility vents spray booth emissions to an incinerator
and reports a 96 percent control efficiency and test report
(the same mass balance documentation is submitted for
uncontrolled emissions).
With a control device, this calculation is no longer a direct
determination and Rule Effectiveness must be applied.
7. The facility reports that 2 Ibs VOC are consumed per 100
pieces, and submits monthly reports of production (pieces).
Rate per unit of production is not suitable for direct
determination where the production is not coating or solvent
used.
C-5
-------
APPENDIX D
DETERMINING SAMPLE SIZE
-------
-------
DETERMINATION OF SAMPLE SIZE
The sample chosen for the RE questionnaire survey should be
representative of the relevant category population as a whole.
This means that the size of the sample must be statistically
adequate to represent that category population. A population
mean or proportion is estimated by the corresponding mean or
proportion of the sample. In addition to the size of the sample
(i.e./ the sources for which a questionnaire is completed), it is
also necessary to consider the makeup of the sample chosen.
For many applications, the population parameters (i.e./.
population mean (i and population standard deviation o) are
usually known or can be estimated. In the case of RE, estimating
these parameters is the objective of the survey. The population
mean can be approximated by the sample mean with some degree of
error. In deciding on size of sample for a given survey/ several
elements must be considered:
The standard deviation of the population from*which the
sample is to be drawn. Lacking this information/ it can be
estimated either from past surveys (if available) from the
same population/ from an initial survey conducted for this
purpose (the first ten sources chosen at random) or from
rational considerations of what this population might look
like.
The degree of accuracy "e" one would like to have in the
sample data. This is usually defined as an interval and is
referred to as the limit of error. The sample mean will
usually not be exactly equal to the population mean. The
size of this difference is the limit of error "e."
• The degree of confidence o one would like to have to be
confident that the population mean is within the limit of
error set above.
Thus, if the sample mean is used as an estimate of the
population mean ji, we can be (1 - o) x 100 percent confident that
the limit of error will be less than a specified amount "e" when
the sample size is at least
1/2
where n = sample size
o = standard deviation of the population
e = limit of error (usually in the range of 5 to 10
percent of the value of the mean)
a = confidence level
Z
-------
a (Percent)
90
95
99
99.7
1/2
1.65
1.96
2.58
3.00
The following tables were developed using the equation
presented above. They show the sensitivity of sample size with
respect to the confidence level a, the limit of error e, and the
standard deviation of the population from which the sample is to
be drawn. There is a trade-off between confidence level and
limit of error. The largest sample size provides the highest
confidence level and lowest limit of error. In addition/ larger
sample sizes are required when the standard deviation is larger.
Conversely, the smallest sample size-provides the lowest
confidence level and the highest limit of error. Smaller sample
sizes can be used when the standard deviation is lower.
The following example illustrates the use of «the tables
presented above. Assume that an air pollution control agency is
interested in estimating rule effectiveness (RE) in the can
coating industry. However, no prior estimates on RE are
available from previous research. Lacking such an estimate, the
initial survey was conducted on 10 facilities. •• Results of the
initial survey yielded an average RE value of 80 percent with a
standard deviation of 8 percent. Assuming a 90 percent
confidence limit and a limit of error of 5 percent, the sample
size required is obtained from Table 1 and is equal to 7. In
this case, the survey for this category would be complete.
However, if the standard deviation obtained from the initial
survey was 10 percent and the limit of error was 5 percent, the
number of facilities required for sampling increases from 7 to 11
facilities, and one more questionnaire would need to be
completed. On the other hand, choosing a larger limit of error,
5.5 percent instead of 5 percent, will yield a sample size of 9
facilities instead of 11.
CHOICE OF SAMPLE SIZE
For statistical purposes, the variables affecting the sample
size are the limit of error and the confidence level. However,
decisions on actual sample size to be used must also include
considerations such as available resources and data quality
requirements. A decision on what sample size to choose should
begin with an estimation of the resources necessary for execution
and data analysis. The initial survey of ten randomly-selected
facilities can be used for that purpose. The second step in
deciding on the size of the sample and the type of survey to be
conducted is to determine the resources available to the
surveying agency including staff time available for completing
the questionnaires. The next step is to determine a sample size
D-3
-------
based on the statistical formulas and estimate the resources
required to conduct the survey. Those resources are then
compared.to the resources available to the agency for the purpose
of conducting the survey. If the resources needed exceed the
available resources, the agency should decide on an affordable
sample size. This is achieved by modifying the acceptable limit
of error or confidence level or both.
EPA recommends that the 90 percent confidence interval
(Table D-l) be used; the suggested sample error is 5 percent, but
should not exceed 10 percent. State and local agencies are
permitted latitude to choose higher confidence intervals and
lower sampling errors. Where these methods are used, the SIP
documentation should state the selected error and confidence
levels.
D-4
-------
TABLE D-l. SENSITIVITY ANALYSIS OF SAMPLE SIZE: CONFIDENCE LEVEL
90%
Sample
Error
2.5%
3.0%
3.5%
4.0%
4.5%
5.5%
6.0%
6.5%
7.0%
7.5%
8.0%
8.5%
9.0%
2%
2
1
1
1
1
0
0
0
0
0
0
0
0
4%
7
5
4
3
2
-A f''<' :.: :.•:. "v. ,ff '.
1
1
1
1
1
1
1
1
6%
16
11
8
6
5
3
3
2
2
2
2
1
1
8%
28
19
14
11
9
j.V.iJpl
6
5
4
4
3
3
2
2
Stan<
10%
44
30
22
17
13
9
8
6
6
5
4
4
3
dard Dei
12%
63
44
32
25
19
13
11
9
e
7
6
5
5
riation
14%
85
59
44
33
26
18
15
13
11
9
8
7
7
16%
112
77
57
44
34
fe 2 8 ":'
23
19
16
14
12
11
10
9
18%
141
98
72
55
44
29
25
21
18
16
14
12
' 11
20%
174
121
89
68
54
^:^:-m:;
36
30
26
22
19
17
15
13
22%
211
146
108
82
44
37
31
27
23
21
18
16
24%
251
174
128
98
77
52
44
37
32
28
25
22
19
-------
TABLE D-2. SENSITIVITY ANALYSIS OF SAMPLE SIZE: CONFIDENCE LEVEL = 95%
Standard Deviation
Sample
Error
2.5%
3.0%
3.5%
4.0%
4.5%
5.5%
6.0%
6.5%
7.0%
7.5%
8.0%
8.5%
9.0%
2%
2
2
1
1
1
S:'4 irf
i
0
0
0
0
0
0
0 .
4%
10
7
5
4
3
2
2
1
1
1
1
1
1
6%
22
15
11
9
7
S- ••$..
5
4
3
3
2
2
2
2
8%
39
27
20
15
12
8
7
6
5
4
4
3
3
10%
61
43
31
24
19
13
11
9
8
7
6
5
5
12%
89
61
45
35
27
"'Ha*.!
18
15
13
11
10
9
8
7
14%
120
84
61
47
37
1" 30
25
21
18
15
13.
12
10
9
16%
157
109
80
61
49
33
27
23
20 .
17
15
14
12
18%
199
138
102
78
61
fl 59 ? •
41
35
29
25
22
19
17
15
20%
246
171
125
96
76
51
43
36
31
27
24
21
19
22%
297
207
152
116
92
61
52
44
38
33
29
26
23
24%
354
246
181
138
109
73
61
52
45
39
35
31
27
-------
TABLE D-3. SENSITIVITY ANALYSIS OF SAMPLE SIZE: CONFIDENCE LEVEL
99%
Standard Deviation
Sample
Error
2.5%
3.0%
3.5%
4.0%
4.5%
5.5%
6.0%
6.5%
7 .0%
7.5%
8.0%
8.5%
9.0%
2%
4
3
2
2
1
ft|:y,"f :r] ;: y £:<:>.!, "•!£ •-£" '•:• :
, ::K^K: 1 &Y1*.": : *:: '. ", " ' :" - '
1
1
1
1
0
0
0
0
4%
17
12
9
7
5
4
3
3
2
2
2
1
1
6%
38
27
20
15
12
8
7
6
5
4
4
3
3
8%
68
47
35
27
21
14
12
10
9
8
7
6
5
10%
107
74
54
42
33
22
18
16
14
12
10
9
8
12%
153
107
78
60
47
32
27
23
20
17
15
13
12
14%
209
145
107
82
64
i!l'7':;£i:l
43
36
31
27
23
20
18
16
16%
273
189
139
107
84 _
56
47
40
35
30
27
24
21
18%
345
240
176
135
107
71
60
51
44
38
34
30
27
20%
426
296
217 .
166
131
88
74
63
54
47
42
37
33
22%
515
358
263
201
107
89
76
66
57
50
45
40
24%
613
426
313
240
189
:•:•:•:• *y :•:-£•••: . K-K-j/1-
153,
127
107
91
78
68
60
53
47
-------
APPENDIX E
DEFAULT CONTROL ASSUMPTIONS FOR CT6 CATEGORIES
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-------
The attached table lists the CTG categories and the approximate
control efficiency which the CTG authors identified .for the CTG
categories. Many of the efficiencies depend on which control
method is used and the solvent content. Closer analysis of the
CTG documents and references would likely improve the rough
estimates provided here. EPA has not determined the validity or
reliability of this listing for the purposes of RE.
E-2
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TABLE E-l.
TYPICAL VOC REDUCTION PER FACILITY FOR CTG
CATEGORIES BASED ON CTG DOCUMENTS
Category
Low* High* Single
(%) (%) Value
Comment
Point Source Categories
Gasoline Loading Terminals
Bulk Gasoline Plants
Alternative 1
Total Plant
All Transfers
Alternative 2
Total Plant
All Transfers
Alternative 3
Total Plant
All Transfers
Fixed Roof Petroleum Tanks
Refinery Processes
VPS
.. WS
PUT
Surface Coating
Cans
Metal Coils
Fabric and Vinyl
Paper Products
Automobiles & Light Duty
Trucks
Prime Coating
Top Coating
Final Repair Coating
Metal Furniture
Magnetic Wire
Large Appliances
60
70
80
80
80
75
NA
50
79
100
98
100
99
93
92
99
95
87
22
27
54
64
77
92
90+
100
95
98
Solvent % and control
dependent
90
(continued)
E-3
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TABLE E-l.
TYPICAL VOC REDUCTION PER FACILITY FOR CTG
CATEGORIES BASED ON CTG DOCUMENTS (continued)
Category
Low' High* Single
(%) (%) Value
Conment
Misc. Metal Parts
Process Modification 50 98
Exhaust Gas Treatment
Flatwood Paneling 70 90
Graphic Arts
Publication Rotogravure
Packaging Rotogravure
Flexographic Printing
Leaks from Petroleum Refineries
External Floating Roof Tanks 33 99
Gasoline Truck Leaks & Vapor NA
Collection
Synthetic Pharmaceutical NA
Manufacturing
Rubber Tire Manufacturing
Carbon Adsorption 62 86
Incineration 59 81
Water-based Coatings
Leaks from NG/Gasoline
Processing Plants
Mfg. of HDPE, PP, and PS Resins
SOC & Polymer Mfg. Equipment
Fugitives
Large Petroleum Dry Cleaners 66 72
SOCMI Air Oxidation Processes
Thermal Oxidation
90+
75
65
60
62 Based on 15,900 mVday
97
72 Model plants
98 Model Plants
36 under RACT
98 With controls above
baseline
53
(continued)
E-4
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TABLE E-l.
TYPICAL VOC REDUCTION PER FACILITY FOR CTG
CATEGORIES BASED ON CTG DOCUMENTS (continued)
Category
Low* High* Single
(%) (%) Value
Comment
Area Sources
Service Stations - Stage I
Transfer Losses
Total Facility
Cutback Asphalt
95+
50
100
Solvent Metal Cleaning
Cold Cleaning 50 53
Open-top Vapor Degreasing 45 60
CD 25 60
Perchloroethylene Dry Cleaners 40 70
+/- 20%
+/- 15%
+/- 10%
*
Carbon Adsorption
Users should select the low value from a range unless another value is
justified. One-hundred percent should never be used unless the emissions are
directly determined or there has been an irreversible process change.
E-5
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